Method and apparatus for transmitting and receiving data in mobile communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. This disclosure also relates to a cell reselection operation. A method of a terminal in a wireless communication system may include receiving a first scheduling information for a first frequency band from a base station, switching a bandwidth to the first frequency band according to the first scheduling information, starting a timer for the first frequency band, and switching the bandwidth to a second frequency band when the timer expires.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application a continuation application of prior application Ser.No. 15/886,273, filed on Feb. 1, 2018, which was based on and claimedpriority under 35 U.S.C. § 119(a) of a Korean patent application Serialnumber 10-2017-0015211, filed on Feb. 2, 2017, in the KoreanIntellectual Property Office, and of a Korean patent application Serialnumber 10-2017-0037174, filed on Mar. 23, 2017, in the KoreanIntellectual Property Office, and of a Korean patent application Serialnumber 10-2017-0101921, filed on Aug. 10, 2017, in the KoreanIntellectual Property Office, and of a Korean patent application Serialnumber 10-2017-0125589, filed on Sep. 27, 2017, in the KoreanIntellectual Property Office, the disclosure of each of which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

The disclosure relates to a mobile communication system. Moreparticularly, the disclosure relates to a cell reselection method of aterminal.

In addition, the disclosure relates to cell measurement and mobilitymanagement operations using signals transmitted by means of beamformingin a beamforming based system.

In addition, the disclosure relates to a method for transmitting areference signal for a terminal in a radio resource control (RRC)connected state.

In addition, the disclosure relates to a method for switching abandwidth of a terminal in a mobile communication system.

BACKGROUND

To meet the demand for wireless data traffic having increased sincedeployment of fourth generation (4G) communication systems, efforts havebeen made to develop an improved fifth generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post long term evolution(LTE) System’. The 5G communication system is considered to beimplemented in higher frequency millimeter wave (mmWave) bands, e.g., 60GHz bands, so as to accomplish higher data rates. To decreasepropagation loss of the radio waves and increase the transmissiondistance, the beamforming, massive multiple-input multiple-output(MIMO), full dimensional MIMO (FD-MIMO), array antenna, an analog beamforming, large scale antenna techniques are discussed in 5Gcommunication systems. In addition, in 5G communication systems,development for system network improvement is under way based onadvanced small cells, cloud radio access networks (RANs), ultra-densenetworks, device-to-device (D2D) communication, wireless backhaul,moving network, cooperative communication, coordinated multi-points(CoMP), reception-end interference cancellation and the like. In the 5Gsystem, hybrid frequency shift key (FSK) and quadrature amplitudemodulation (QAM) (FQAM) and sliding window superposition coding (SWSC)as an advanced coding modulation (ACM), and filter bank multi carrier(FBMC), non-orthogonal multiple access (NOMA), and sparse code multipleaccess (SCMA) as an advanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofeverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing information technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RAN as theabove-described Big Data processing technology may also be considered tobe as an example of convergence between the 5G technology and the IoTtechnology.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea method for preferentially reselecting a specific cell by a terminal,thereby enabling quick data transmission and reception of a terminal andpreventing an increase in signaling overhead occurring in a datatransmission/reception preparation procedure.

Another aspect of the disclosure is to provide a system, method andapparatus for performing cell measurement and mobility managementoperations using signals transmitted by means of beamforming in abeamforming based system including one or more base stations (BS) andone or more terminals.

Another aspect of the disclosure to provide a method and apparatus fortransmitting a reference signal for a terminal in a radio resourcecontrol (RRC) connected state.

Another aspect of the disclosure is to provide a procedure of receivinga base station signal in a limited band by considering power consumptionof a terminal in a single carrier and also provide a method for a basestation and a terminal to utilize the entire system band flexibly anddynamically. Also, the disclosure provides a method and a procedure fora terminal to save power in such a flexible bandwidth system.

In accordance with an aspect of the disclosure, a method of a terminalin a wireless communication system is provided. The method includesreceiving a first scheduling information for a first frequency band froma base station, switching a bandwidth to the first frequency bandaccording to the first scheduling information, starting a timer for thefirst frequency band, and switching the bandwidth to a second frequencyband when the timer expires.

In accordance with another aspect of the disclosure, a method of a basestation in a wireless communication system is provided. The methodincludes transmitting a first scheduling information for a firstfrequency band to a terminal, switching a bandwidth to the firstfrequency band according to the first scheduling information, starting atimer for the first frequency band, and switching the bandwidth to asecond frequency band when the timer expires.

In accordance with another aspect of the disclosure, a terminal in awireless communication system is provided. The terminal includes atransceiver and a controller configured to receive a first schedulinginformation for a first frequency band from a base station, switch abandwidth to the first frequency band according to the first schedulinginformation, start a timer for the first frequency band, and switch thebandwidth to a second frequency band when the timer expires.

In accordance with another aspect of the disclosure, a base station in awireless communication system is provided. The base station includes atransceiver and a controller configured to transmit a first schedulinginformation for a first frequency band to a terminal, switch a bandwidthto the first frequency band according to the first schedulinginformation, start a timer for the first frequency band, and switch thebandwidth to a second frequency band when the timer expires.

In accordance with another aspect of the disclosure, a terminal mayreselect a specific cell capable of fast data transmission/reception,thereby preventing an increase in signaling overhead that may occur in adata transmission/reception preparation procedure.

In accordance with another aspect of the disclosure, each base stationmay transmit two or more reference signals, generated by differentsignal generation rules, by using two or more beams having differentbeam areas, coverages, transmission periods, and the like.

In accordance with another aspect of the disclosure, a base station maydetermine a beam to be used for data transmission by transmitting areference signal for a terminal in an RRC connection state, and use thedetermined beam for data transmission/reception.

In accordance with another aspect of the disclosure, a base station maycontrol a plurality of terminals using various sizes of bands to useresources evenly in the operating band of the system. In addition, thebase station allows the terminal to perform scheduling, modulation andcoding scheme (MCS), channel state indication (CSI) reporting,measurement, and the like within a configured partial band, therebyminimizing a reduction of scheduling and handover performance in theentire band. Also, if a connection problem occurs in such a partialband, the terminal may recover it within a short delay.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a diagram illustrating a situation in which a user equipment(UE) moves in a radio access network (RAN) area after transitioning froma connected mode to an inactive mode according to an embodiment of thedisclosure;

FIG. 2 is a diagram illustrating the operation of an inactive mode UEthat receives downlink (DL) data from a g node B (gNB) having a validcell radio network temporary identifier (C-RNTI) according to anembodiment of the disclosure;

FIG. 3 is a diagram illustrating the operation of an inactive mode UEthat receives DL data from all gNBs in a RAN area through an area cellradio network temporary identifier (A-RNTI) according to an embodimentof the disclosure;

FIG. 4 is a diagram illustrating the operation of an inactive mode UEthat receives a paging signal from all gNBs in a RAN area through anA-RNTI, performs a 2-step random access channel (RACH), and receives DLdata from a gNB receiving an RACH preamble through an A-RNTI accordingto an embodiment of the disclosure;

FIG. 5 is a diagram illustrating the operation of an inactive mode UEthat receives a paging signal from all gNBs in a RAN area through anA-RNTI, performs a 4-step RACH, and receives DL data from a gNBreceiving an RACH preamble through an A-RNTI according to an embodimentof the disclosure;

FIG. 6 is a diagram illustrating a difference between a gNB having avalid C-RNTI and a gNB having no valid C-RNTI in cell reselection of aninactive mode UE according to an embodiment of the disclosure;

FIG. 7 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having a validC-RNTI to a gNB having no valid C-RNTI according to an embodiment of thedisclosure;

FIG. 8 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having no validC-RNTI to a gNB having a valid C-RNTI according to an embodiment of thedisclosure;

FIG. 9 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having no validC-RNTI to another gNB having no valid C-RNTI according to an embodimentof the disclosure;

FIG. 10 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having a validC-RNTI to another gNB having a valid C-RNTI according to an embodimentof the disclosure;

FIG. 11 is a diagram illustrating that different types of referencesignals having the same period are transmitted through differentfrequency bands according to an embodiment of the disclosure;

FIG. 12 is a diagram illustrating that different types of referencesignals having the same period are transmitted through the samefrequency band according to an embodiment of the disclosure;

FIG. 13 is a diagram illustrating that different types of referencesignals having different periods are transmitted through the samefrequency band according to an embodiment of the disclosure;

FIG. 14 is a diagram illustrating a method for a terminal to calculate ameasured value of a cell which transmits different reference signalsaccording to an embodiment of the disclosure;

FIG. 15 is a diagram illustrating a method for classifying measuredsignals into reference signals of the same type and calculating a cellrepresentative value by using measured values according to an embodimentof the disclosure;

FIG. 16 is a diagram illustrating a method for calculating a cellrepresentative value by using all measured reference signals accordingto an embodiment of the disclosure;

FIG. 17 is a diagram illustrating a method for calculating a cellrepresentative value according to an embodiment of the disclosure;

FIGS. 18 and 19 show examples of a signal transmitted to a terminal by abase station and utilized to calculate a cell measured value accordingto an embodiment of the disclosure;

FIG. 20 is a diagram illustrating an example of a signal includingweights transmitted to a terminal by a base station according to anembodiment of the disclosure;

FIG. 21 is a diagram illustrating a method for a terminal to calculate acell representative value for each reference signal (RS) from differentRSs through a separate procedure according to an embodiment of thedisclosure;

FIG. 22 is a diagram illustrating a method for controlling a change ofmobility by using different types of reference signals according to anembodiment of the disclosure;

FIG. 23 shows a method for calculating representative values forrespective RSs through separate procedures for different types of RSsand then determining one cell representative value by using the aboverepresentative values according to an embodiment of the disclosure;

FIG. 24 shows a method for multiplying each beam measurement signal bythe same weight with respect to the same type of RSs and thendetermining a cell representative value according to an embodiment ofthe disclosure;

FIG. 25 shows a method for selecting a specific number of beammeasurement signals with respect to different types of RSs, multiplyinga representative value for each RS by a weight, and thereby deriving acell representative value according to an embodiment of the disclosure;

FIG. 26 shows a method for selecting a specific number of beammeasurement signals with respect to different types of RSs, calculatinga representative value for each RS type by multiplying each selectedbeam measurement signal by a weight, and deriving a cell representativevalue by multiplying the representative value for each RS type by aweight according to an embodiment of the disclosure;

FIG. 27 shows another method for selecting a different number of beammeasurement signals with respect to different types of RSs and thenderiving a cell representative value by multiplying the selected signalsby different weights according to an embodiment of the disclosure;

FIG. 28 is a diagram illustrating a method for deriving a cellrepresentative value by multiplying all beam measurement signals bydifferent weights with respect to different types of RSs according to anembodiment of the disclosure;

FIG. 29 is a diagram illustrating a method for controlling a mobilitychange by using different types of reference signals according to anembodiment of the disclosure;

FIG. 30 is a diagram illustrating a terminal according to an embodimentof the disclosure;

FIG. 31 is a diagram illustrating a base station according to anembodiment of the disclosure;

FIG. 32 is a flow diagram illustrating an initial access operationaccording to an embodiment of the disclosure;

FIG. 33 is a flow diagram illustrating a handover operation according toan embodiment of the disclosure;

FIG. 34 is a flow diagram illustrating an operation according to anembodiment of the disclosure;

FIGS. 35 to 41 are flow diagrams illustrating various methods fordetermining a beam to be used for data transmission and reception in ahandover process according to embodiments of the disclosure;

FIG. 42 is a flow diagram illustrating a random access operationaccording to an embodiment of the disclosure;

FIGS. 43 to 47 are flow diagrams illustrating various methods fordetermining a beam to be used for data transmission and reception in arandom access process according to various embodiments of thedisclosure;

FIG. 48 is a diagram illustrating a long term evolution (LTE) scalablebandwidth (BW) system according to an embodiment of the disclosure;

FIG. 49 is a diagram illustrating features of a fifth generation (5G)new radio (NR) flexible BW system according to an embodiment of thedisclosure;

FIG. 50 is a diagram illustrating various band division schemes in a 5GNR flexible BW system according to an embodiment of the disclosure;

FIG. 51 is a diagram illustrating a self/cross-band scheduling operationaccording to an embodiment of the disclosure;

FIGS. 52 to 54 are diagrams illustrating examples of BW expansion andreduction operation by a physical layer control signal according tovarious embodiments of the disclosure;

FIGS. 55 to 58 are diagrams illustrating examples of BW expansion andreduction operation by physical layer and radio resource control (RRC)control signals according to various embodiments of the disclosure;

FIGS. 59 and 60 are diagrams illustrating examples of connected modediscontinuous reception (C-DRX) operation for adaptive BW according tovarious embodiments of the disclosure;

FIG. 61 is a diagram illustrating an example of discontinuous reception(DRX) setup for a wide band and a narrow band according to an embodimentof the disclosure;

FIGS. 62 and 63 are diagrams illustrating examples of DRX setup and apriority rule for a wide band and a narrow band according to variousembodiments of the disclosure;

FIG. 64 is a flow diagram illustrating an operation of a terminalaccording to an embodiment of the disclosure;

FIG. 65 shows a DRX operation for a transmit time interval (TTI) changeaccording to an embodiment of the disclosure;

FIG. 66 is a diagram illustrating an example of determining a TTI valuebased on to a control channel monitoring periodicity and a transmissionduration according to an embodiment of the disclosure;

FIGS. 67 to 71 are diagrams illustrating a timer-based band switchingoperation according to various embodiments of the disclosure;

FIG. 72 is a diagram illustrating a configuration of a terminalaccording to an embodiment of the disclosure; and

FIG. 73 is a diagram illustrating a configuration of a base stationaccording to an embodiment of the disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

The advantages and features of the disclosure and the manner ofachieving them will become apparent through embodiments described indetail below with reference to the accompanying drawings. The disclosuremay, however, be embodied in many different forms and should not beconstrued as limited to embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the disclosure to thoseskilled in the art. The disclosure is only defined by the scope ofclaims. Like reference numerals refer to like elements throughout thisdisclosure.

First Embodiment

In a new radio (NR), which is currently being discussed in thirdgeneration partnership project (3GPP), the introduction of an inactivemode in addition to a connected mode and an idle mode defined in longterm evolution (LTE) has been decided. The features and requirements ofthe inactive mode are as follows.

-   -   Signaling and resource usage in the radio access network (RAN)        and the core network (CN) should be minimized.    -   Time required up to data transmission in the inactive mode        should be minimized. Here, the data transmission may be        performed while the user equipment (UE) maintains the inactive        mode or is in the connected mode.    -   Paging by the RAN as well as the existing paging by the CN of        LTE should be supported.    -   A RAN-based notification area (hereinafter, a RAN area) is        defined. In the RAN area, the UE moves without location update.        The g Node Bs (gNBs) in the RAN area maintain the access stratum        (AS) context of the UE.

According to the above requirements, the inactive mode UE should be ableto perform operations for fast data transmission/reception. One of themis a cell reselection. Basically, as in the above requirements, theinactive mode UE moves within the RAN area without location update.However, if the inactive mode UE performs a cell reselection through thesame operation as the idle mode UE in the existing LTE, it may beunsuitable in view of fast data transmission/reception.

FIG. 1 is a diagram illustrating a situation in which a UE moves in aRAN area after transitioning to an inactive mode according to anembodiment of the disclosure.

Referring to FIG. 1 , an environment of the disclosure is illustrated.In this environment or situation shown in FIG. 1 , a RAN notificationarea is formed of a plurality of gNBs which are classified into a gNB110 having a cell radio network temporary identifier (C-RNTI) valid forthe inactive mode UE and a gNB 120 having no valid C-RNTI. The inactivemode UE is moving freely within the RAN notification area.

In a situation of FIG. 1 , the UE which has been connected to the gNB110 having the C-RNTI transitions from the connected mode to theinactive mode and then moves freely in the RAN area.

In FIG. 1 , the gNB 110 which has provided lastly a service to the UEmaintains the C-RNTI used by the UE according to the definition of theinactive mode in which the AS context of the UE is maintained.Therefore, if the inactive mode UE transmits and receives data to andfrom the gNB 110, it is not necessary to reconfigure the C-RNTI.

On the other hand, the gNB 120 has no C-RNTI of the inactive mode UEeven though the gNB 120 belongs to the RAN area of the UE. Therefore,when the inactive mode UE communicates with the gNB 120, not the gNB 110having the C-RNTI of the UE, while moving in the RAN area, the gNB 120needs a procedure of allocating the C-RNTI to the UE. This may increasea delay in data transmission and reception of the inactive mode UE.

In 3GPP, the introduction of a separate radio network temporaryidentifier (RNTI) for data transmission/reception of the inactive modeUE is being discussed. In the disclosure, this is referred to as an areaRNTI (A-RNTI). The A-RNTI is an identifier designed to allow all UEs inthe RAN area to be uniquely assigned. Since the RAN area includes aplurality of cells, the A-RNTI has a greater overhead than the C-RNTIdesigned to allow the UEs in the cell to be uniquely assigned.

FIGS. 2 to 5 below illustrate the operation of the inactive mode UE thatreceives DL data from the gNB in the RAN area according to an embodimentof the disclosure.

FIG. 2 is a diagram illustrating the operation of the inactive mode UEthat receives downlink (DL) data from the gNB having a valid C-RNTIaccording to an embodiment of the disclosure.

Referring to FIG. 2 , since the gNB has the C-RNTI, the gNB may transmitdata by using the C-RNTI at operation S210.

FIGS. 3 to 5 are diagrams illustrating the operation of the inactivemode UE that receives DL data from the gNB that does not maintain theC-RNTI in the RAN area according to an embodiment of the disclosure.

Referring to FIG. 3 , FIG. 3 shows that all gNBs belonging to the RANarea transmit DL data to the inactive mode UE by using the A-RNTI atoperation S310. Since the UE is actually adjacent to one gNB in mostcases, it is inefficient utilization of resources that all gNBs in theRAN area transmit DL data by using the unique A-RNTI.

FIGS. 4 and 5 are diagrams illustrating the operation of the inactivemode UE that identifies an adjacent gNB by performing a 2-step or 4-steprandom access channel (RACH) and receives DL data from the adjacent gNBaccording to an embodiment of the disclosure.

First, all gNBs belonging to the RAN area perform paging by using theA-RNTI of the UE at operation S410 or S510. Then, the UE responding tothe paging performs a 2-step or 4-step RACH and inform, via the RACHmessage 1 (S420) or the RACH message 3 (S520), the gNB that the UEcorresponds to the A-RNTI contained in the paging signal. The gNB thatreceives this message understands that the inactive mode UE is locatednearby, and transmits DL data. This operation causes overhead becauseall gNBs in the RAN area transmit paging signals. Also, other overheadoccurs in a procedure in which the UE has to perform the 2-step or4-step RACH operation.

Referring to FIGS. 2 to 5 , when the gNB has the valid C-RNTI, the datatransmission/reception of the inactive mode UE has the least delay andneeds the least signaling of the UE and the gNB. Therefore, it isadvantageous for the inactive mode UE to stay around the gNB having thevalid C-RNTI as long as possible. This aspect should be reflected in thecell reselection operation of the inactive mode UE. The disclosureproposes a cell selection operation that allows the inactive mode UE tostay around the gNB having the valid C-RNTI as long as possible.

First, the cell reselection operation of the UE in LTE will bedescribed. In LTE, the cell reselection of the idle mode UE refers to anoperation of selecting a cell by the UE for camping on, acquiring systeminformation, maintaining synchronization, and receiving a paging signal.In order to understand the cell reselection operation, it is necessaryto understand the cell selection operation. The cell selection includesthe operation of measuring and inducing the following Srxlev andchecking whether Srxlev is greater than zero (details are the same asLTE standard and thus will be omitted herein). Here, Srxlev is composedof Qrxlevmeas, Qrxlevmin, Qrxlevminoffset, and Pcompensation. Qrxlevmeascorresponds to a reference signal received power (RSRP) value measuredby the UE, and the others, Qrxlevmin, Qrxlevminoffset, andPcompensation, are parameters notified to the UE by the gNB throughsystem information, a radio resource control (RRC) message, or the like.

TABLE 1 Cell selection criterion: S   Suitable cells  Srxlev > 0  Srxlev = Qrxlevmeas − (Qrxlevmin − Qrxlevminoffset) − Pcompensation  Pcompensation = max(UE_TXPWR_MAX_RACH − P_MAX, 0)

Based on the concept of suitable cells described above, i.e., Srxlev>0,the cell reselection is performed through the following operations inLTE. First, the UE measures the signal strength for the currentlycamping cell (i.e., serving cell) and neighbor cells, and then derivesRs and Rn. Here, Q_(meas,s) and Q_(meas,n) denote the signal strength(RSRP) for the serving cell and the neighbor cell, respectively. Also,Q_(hyst,s) and Q_(offset,n) are parameters that the gNB provides to theUE to prevent frequent cell reselection. After measuring the signalstrength for cells, the UE selects a cell having the highest Rs or Rnamong cells having Srxlev greater than zero and then performs camping onthe selected cell. If the currently camping cell and the newly selectedcell are different from each other, this means the UE performs the cellreselection.

TABLE 2 Cell ranking criterion: R   Ranking of cells  Rs = Qmeas,s +Qhyst,s  Rn = Qmeas,n − Qoffset,s,n Reselected cell  Suitable (Scriterion) and  Best rank (highest R)

Described above is a cell reselection process of the idle mode UE inLTE. Meanwhile, in the inactive mode which is expected to be newlyintroduced in NR, it is advantageous for the UE to stay in a cell havinga valid C-RNTI as long as possible in view of fast datatransmission/reception of the inactive mode UE. Considering this,proposed is a cell reselection operation suitable for fast datatransmission/reception of the inactive mode UE. In this disclosure, theterm cell is used interchangeably with a base station, a gNB, or an eNode B (eNB), all of which have the same meaning.

The disclosure proposes a method for allowing an inactive mode UE tostay as long as possible in a gNB having a C-RNTI valid for the UE byapplying an additional offset to the gNB regardless of whether a certaincell is a serving cell or a neighbor cell in a cell reselection.

FIG. 6 is a diagram illustrating a cell reselection method of aninactive mode UE according to an embodiment of the disclosure.

Referring to FIG. 6 , for a gNB 610 having a valid C-RNTI for theinactive mode UE, the UE adds an additional offset, QC-RNTI, in the cellreselection and applies it to cell ranking. On the other hand, for a gNB620 having no valid C-RNTI for the inactive mode UE, the UE performscell ranking without additional offset.

The basic cell reselection operation is the same as described above. Incase of the gNB having the valid C-RNTI of the inactive mode UE as shownin FIG. 6 , the UE may apply an additional offset (referred to asQ_(C-RNTI) herein). According to the disclosure, for the gNB that doesnot have the valid C-RNTI for the inactive mode UE, the UE does notapply an additional offset (Q_(C_RNTI)). The cell reselection equationaccording to the disclosure is as follows.

TABLE 3 Cell ranking criterion for inactive mode UE: Rinactive   Rankingof cells  Rs = Qmeas,s + Qhyst,s + Q_(C-RNTI,s)  Rn = Qmeas,n −Qoffset,s,n + Q_(C-RNTI,n)   Q_(C-RNTI,s) = X (if cell s has validC-RNTI for inactive mode UE) or 0 (if   cell s does not have validC-RNTI for inactive mode UE)   Q_(C-RNTI,n) = Y (if cell n has validC-RNTI for inactive mode UE) or 0 (if   cell n does not have validC-RNTI for inactive mode UE)   X and Y are configured by gNB via RRCsignaling or system information Reselected cell  Suitable (S criterion)and  Best rank (highest R)

Alternatively, the cell reselection equation according to the disclosureis as follows.

TABLE 4 Cell ranking criterion for inactive mode UE: Rinactive   Rankingof cells  Rs = Qmeas,s + Qhyst,s + Q_(C-RNTI,s)  Rn = Qmeas,n −Qoffset,s,n   Q_(C-RNTI,s) = X (If cell s has valid C-RNTI for inactivemode UE) or 0 (if   cell s does not have valid C-RNTI for inactive modeUE)   Xis configured by gNB via RRC signaling or system information

The inactive mode UE performs a cell reselection operation according tothe above equation in the following three situations as shown in FIGS. 7to 9 .

FIG. 7 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having a validC-RNTI to a gNB having no valid C-RNTI according to an embodiment of thedisclosure.

Referring to FIG. 7 , it is assumed that the UE is currently camping onthe gNB 710 having the valid C-RNTI. According to the disclosure, it isadvantageous in view of fast data transmission/reception that the UEremains as long as possible in the current serving cell, i.e., the gNB710 having the valid C-RNTI. Therefore, when deriving Rs for the currentserving cell in the ranking process for cell reselection, the UE addsQ_(C-RNTI,s) in addition to Q_(meas,s) and Q_(hyst,s).

However, since the gNB 720 to which the UE is moving does not have thevalid C-RNTI for the UE, the UE does not apply any additional offsetother than Q_(meas,n) and Q_(offset,n). In this example, the inactivemode UE derives Rs and Rn in this manner and compares them to performthe final cell reselection.

TABLE 5 Example of equation related to FIG. 7   Rs = Q_(meas,s) +Q_(hyst,s) + Q_(C-RNTI,s) (= X dB) Rn = Q_(meas,n) − Q_(offset,s,n)Q_(C-RNTI,n) = 0

FIG. 8 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having no validC-RNTI to a gNB having a valid C-RNTI according to an embodiment of thedisclosure.

Referring to FIG. 8 , it is assumed that the UE is currently camping onthe gNB 820 having no valid C-RNTI. According to the disclosure, it isadvantageous in view of fast data transmission/reception that the UEremains as long as possible in a neighbor cell, i.e., the gNB 810 havingthe valid C-RNTI, rather than in the current serving cell, i.e., the gNB820 having no valid C-RNTI. Therefore, when deriving Rs for the currentserving cell in the ranking process for cell reselection, the UE doesnot apply any additional offset other than Q_(meas,s) and Q_(hyst,s).

However, since the gNB 810 to which the UE is moving does not have thevalid C-RNTI for the UE, the UE adds Q_(C-RNTI,n) in addition toQ_(meas,n) and Q_(offset,s,n). In this example, the inactive mode UEderives Rs and Rn in this manner and compares them to perform the finalcell reselection.

TABLE 6 Example of equation related to FIG. 8   Rs = Q_(meas,s) +Q_(hyst,s) Rn = Q_(meas,n) − Q_(offset,s,n) + Q_(C-RNTI,n) (= Y dB)Q_(C-RNTI,s) = 0

FIG. 9 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having no validC-RNTI to another gNB having no valid C-RNTI according to an embodimentof the disclosure.

Referring to FIG. 9 , it is assumed that the UE is currently camping onthe gNB 920 having no valid C-RNTI. The disclosure produces an effectdifferent from the conventional method when the cell reselection isperformed between a gNB having a C-RNTI and a gNB having no C-RNTI.Therefore, in the situation of FIG. 9 , the cell reselection operationis similar to conventional one. That is, when deriving Rs for thecurrent serving cell in the ranking process for cell reselection, the UEdoes not apply any additional offset other than Q_(meas,s) andQ_(hyst,s). In addition, when deriving Rn for a neighbor cell, the UEthe UE does not apply any additional offset other than Q_(meas,n) andQ_(hyst,n). In this example, the inactive mode UE derives Rs and Rn inthis manner and compares them to perform the final cell reselection.

TABLE 7 Example of equation related to FIG. 9   Rs = Q_(meas,s) +Q_(hyst,s) Rn = Q_(meas,n) − Q_(offset,s,n) Q_(C-RNTI,s) = Q_(C-RNTI,n)= 0

FIG. 10 is a diagram illustrating a cell reselection operation in asituation where an inactive mode UE moves from a gNB having a validC-RNTI to another gNB having a valid C-RNTI according to an embodimentof the disclosure.

In an environment where cooperative transmission/reception is performed,a plurality of base stations may have a C-RNTI. In this situation, whenderiving Rs for the current serving cell in the ranking process for cellreselection, the UE may apply additional offset in addition toQ_(meas,s) and Q_(hyst,s). Also, when deriving Rn for a neighbor cell,the UE may apply additional offset in addition to Q_(meas,n) andQ_(offset,s,n). In this example, the inactive mode UE derives Rs and Rnin this manner and compares them to perform the final cell reselection.

TABLE 8 Example of equation related to FIG. 10   Rs = Q_(meas,s) +Q_(hyst,s) + Q_(C-RNTI,s) (= X dB) Rn = Q_(meas,n) − Q_(offset,s,n) +Q_(C-RNTI,n) (= Y dB)

Proposed in the disclosure is a method for allowing the UE to stay aslong as possible in the gNB having the valid C-RNTI by applying anadditional offset to the gNB having the valid C-RNTI when the inactivemode UE performs cell reselection. Although the gNB having the validC-RNTI is exemplarily used in this disclosure, the disclosure can beextended to any base station. Herein, such a base station includes thefollowing examples.

-   -   Example 1: Macro cell    -   Example 2: Home cell (HeNB)    -   Example 3: Specific cell assigned to a UE through system        information or RRC signaling by a base station    -   Example 4: Cell using a specific frequency, e.g., 6 GHz, or less        or more    -   Example 5: Cells installed and operated by a specific operator

Therefore, when the disclosure is applied, the UE can preferentiallyperform the cell reselection for the cell as described above.

Second Embodiment

With the emergence of smart phones, the traffic of smart phones isincreasing exponentially, and there is a growing demand for an increaseof battery life of smart phones. This means that efficient power savingtechnique is required, and thus the power saving mode operation of aterminal is needed. Various techniques have been proposed andstandardized so that the terminal can operate in power saving mode morefrequently and reestablish the network connection more quickly.

In order to accomplish a higher data transfer rate, the fifth generation(5G) communication system considers implementation at a super-highfrequency (mmWave) band (e.g., such as a 60 GHz band). In order toobviate a path loss of a radio wave and increase a delivery distance ofa radio wave at the super-high frequency band, various techniques suchas a beamforming, a massive multiple-input multiple-output (MIMO), afull dimensional MIMO (FD-MIMO), an array antenna, an analogbeam-forming, and a large scale antenna are discussed in the 5Gcommunication system.

Additionally, for an improvement in network of the 5G communicationsystem, technical developments are made in an advanced small cell, acloud radio access network (cloud RAN), an ultra-dense network, a deviceto device (D2D) communication, a wireless backhaul, a moving network, acooperative communication, coordinated multi-points (CoMP), a receptioninterference cancellation, and the like.

Besides, in the 5G communication system, a hybrid frequency shift keyand quadrature amplitude modulation (FQAM) and a sliding windowsuperposition coding (SWSC) are developed as advanced coding modulation(ACM) schemes, and a filter bank multi carrier (FBMC), a non orthogonalmultiple access (NOMA), and a sparse code multiple access (SCMA) arealso developed as advanced access techniques.

In a communication system, a terminal needs an initial cell selectionmethod and a cell reselection method in an idle mode for selecting thebest base station to access. Also, in a connected mode, a terminalshould perform a radio resource management (RRM) measurement so as toperform handover to move to a better cell. In order to select cells andcompare the performance of cells, each terminal should be able toobserve or calculate a measured value representative of each cell or avalue derived from the measured value. In order to achieve this, in LTE,different base stations reserve orthogonal resources in a sharedfrequency band using the omni-beam and transmit a cell specificreference signal of each cell. The terminal measures this signal andthus knows the reference signal received power (RSRP) of each cell.

Also, in a next generation communication system that considersbeamforming, various methods in which different base stations transmitcell and beam specific reference signals on different resources whileusing different beams and a terminal derives a representative valuecorresponding to a certain cell by using measured values of a pluralityof beams transmitted in the cell are needed.

In addition, when base stations transmit two or more types of referencesignals generated by different signal generation rules using two or morebeams having different beam areas, coverages, transmission periods,etc., a method for deriving a representative value corresponding to acertain cell has not been studied yet.

The disclosure relates to a next generation wireless communicationsystem and, more particularly, to a system, method, and apparatus forperforming cell measurement and mobility management operations usingsignals transmitted by means of beamforming in a beamforming-basedsystem including one or more base stations and one or more terminals.

Also, the disclosure relates to a procedure for a beam measurement, abeam measurement report, and a handover start in a wireless systemhaving a base station and a terminal each of which uses multipleantennas.

The disclosure provides a method for a beam-measuring entity (i.e., aterminal) to derive a representative value of a beam-using entity (i.e.,a base station) by using observed and measured beam information in awireless communication having a base station and a terminal each ofwhich uses multiple antennas, especially in a system and environmentusing beamforming of multiple antennas, and also provides a triggercondition for transmitting a beam measurement report by using thederived representative value of the beam-using entity.

The disclosure provides a trigger condition for a beam-using entity(i.e., a base station) to transmit a signal for additional beammeasurement to a beam-measuring entity (i.e., a terminal) by using abeam measured value or a representative value of the beam-using entityreported by the beam-measuring entity, whether a specific condition issatisfied, or the like in a wireless communication having a base stationand a terminal each of which uses multiple antennas, especially in asystem and environment using beamforming of multiple antennas.

The disclosure provides a procedure that, using a beam measured value ora representative value of a beam-using entity (i.e., a base station)reported by a beam-measuring entity (i.e., a terminal), whether aspecific condition is satisfied, or the like, the beam-using entityexchanges information with a neighbor beam-using entity (i.e., aneighbor base station) related to the report of the beam-measuringentity and thereby enables the neighbor beam-using entity to transmit asignal for additional beam measurement in a wireless communicationhaving a base station and a terminal each of which uses multipleantennas, especially in a system and environment using beamforming ofmultiple antennas.

<Method for Transmitting and Receiving Two or More Different Types ofReference Signals>

FIGS. 11 to 13 are diagrams illustrating a method for transmittingdifferent types of reference signals according to various embodiments ofthe disclosure.

Referring to FIG. 11 , as indicated by reference numeral 1100, differenttypes of reference signals (RSs) having the same period may betransmitted using different frequency bands on the same time resource.

Referring to FIG. 12 , alternatively, as indicated by reference numeral1200, different types of RSs having the same period may be transmittedusing the same frequency band on different time resources.

Referring to FIG. 13 , alternatively, as indicated by reference numeral1300, different types of RSs having different periods may be transmittedusing the same frequency band on different time resources.

In addition, different types of reference signals having differentperiods may be transmitted using the same or different sequences on thesame or different time and frequency resources.

<Method for a Terminal to Calculate a Cell Measured Value>

Signals having different beam characteristics are significantlydifferent in received signal strength and transmission performance. Forexample, when a terminal receives a signal at the same position, a widebeam has lower RSRP and lower received signal quality (a channel qualityindicator (CQI), reference signal received quality (RSRQ),signal-to-interference ration (SINR), signal-to-noise ratio (SNR)),compared to a narrow beam, since the power is dispersed.

Like this, when different reference signals having different beamcharacteristics are transmitted by base station(s), antenna(s), ortransmission point(s) in a cell, a terminal may measure differentreference signals. In this case, reference signal measured values mayshow a relative difference according to the beam characteristics asmentioned above.

FIG. 14 is a diagram illustrating a method for a terminal to calculate ameasured value of a cell which transmits different reference signalsaccording to an embodiment of the disclosure.

Referring to FIG. 14 , the terminal may receive and measure allreference signals at operation S1410. Then, the terminal may classifythe received reference signals into reference signals (RSs) of the sametype at operation S1420. For example, the terminal may distinguishsynchronization signals (SSs), cell specific reference signals (RSs),and beam specific RSs. In addition, the terminal may distinguish signalshaving the same sequence generation rule and function from othersignals.

Then, using measured values of the classified reference signals, theterminal may calculate a cell representative value at operation S1430.

Thereafter, using the cell representative value, the terminal may selecta cell of an idle mode or perform RRM measurement at operation S1440.

FIG. 15 is a diagram illustrating a method for classifying measuredsignals into reference signals of the same type and calculating a cellrepresentative value by using measured values according to an embodimentof the disclosure.

Referring to FIG. 15 , the terminal may classify received signals bytype. Then, the terminal may calculate a cell representative value 1500by using measured values of the classified signals, and use thecalculated cell representative value for the idle mode cell selection,the connected mode RRM measurement, or the like.

There are various methods for calculating the cell representative valueby using measurement results of same type signals transmitted on beamshaving the same characteristics. For example, measured values may besummed up, averaged, weighted summed, or weighted averaged. The measuredvalue may be a value obtained by applying L1 filtering or L3 filteringto the result of measurement through sweeping of a base station beam anda terminal beam. In this case, the measured value may be calculated as asingle value through a method such as summation, average, weightedsummation, or weighted average before and after L1 filtering or beforeand after L3 filtering, and then the cell representative value may beobtained through a subsequent process. In addition, the measured valuemay be measured for each beam pair, for the same base station beam, orfor the same terminal beam. These methods may be equally used as amethod for calculating a cell representative value by using only onetype signals according to the present patent.

FIG. 16 is a diagram illustrating a method for calculating a cellrepresentative value by using all measured reference signals accordingto an embodiment of the disclosure.

Referring to FIG. 16 , a cell representative value 1600 may becalculated through a method 1610 such as summation, average, weightedsummation, or weighted average for a beam of best signal strength, Nbeams of good signal strength, or all beams. In this case, the measuredvalue may be calculated for each beam, and the above-described methodsfor calculating the cell representative value may be used.

FIG. 17 is a diagram illustrating a method for calculating a cellrepresentative value according to an embodiment of the disclosure.

Referring to FIG. 17 , the terminal may identify the types of theclassified reference signals, select one or more reference signal types,and calculate the cell representative value.

Specifically, the terminal may select a reference signal type 1 atoperation 1710 and calculate a cell representative value 1700 by usingmeasured values of reference signals transmitted on various beamsincluded in the selected type. Of course, the above-described methodsfor calculating the cell representative value by using only beamsincluded in reference signals of the same type may be used.

Referring to FIG. 17 , a rule used by the terminal to select a specifictype of reference signal and calculate a representative value of acorresponding cell may be already determined in the system including theterminal and the base station. Therefore, the terminal and the basestation may know in advance such a rule without special informationexchange and signal transmission. Such rules for selecting a referencesignal may be determined by considering one or more of the followingexamples:

If a reference signal beam of a particular type prioritized in thestandard is observed and measured, the terminal may calculate the cellrepresentative value with only the reference signal beam of thatparticular type. For example, when a beam specific reference signal(beam RS, additional RS, beamformed demodulation RS (DM-RS), channelstate indicator (CSI)-RS (CSI-RS), etc.) is measured, the terminal maycalculate the cell representative value by using only the correspondingreference signal type.

Alternatively, if a reference signal type having a narrower beam widththan other types is observed and measured, the terminal may prioritizethe reference signal type having the narrowest beam width and calculatethe cell representative value by using only this reference signal type.

Alternatively, if a reference signal type having a wider beam width thanother types is observed and measured, the terminal may prioritize thereference signal type having the widest beam width and calculate thecell representative value by using only this reference signal type.

Alternatively, if a reference signal type transmitted more frequentlythan other types is observed and measured, the terminal may prioritizethe most frequently transmitted reference signal type and calculate thecell representative value by using only this reference signal type.

Alternatively, if a reference signal type transmitted more sparsely thanother types is observed and measured, the terminal may prioritize themost sparsely transmitted reference signal type and calculate the cellrepresentative value by using only this reference signal type.

Alternatively, if a reference signal type transmitted in a widercoverage than other types is observed and measured, the terminal mayprioritize the reference signal type transmitted in the widest coverageand calculate the cell representative value by using only this referencesignal type.

Alternatively, if a reference signal type transmitted in a smallercoverage than other types is observed and measured, the terminal mayprioritize the reference signal type transmitted in the smallestcoverage and calculate the cell representative value by using only thisreference signal type.

In another embodiment, the terminal may manage mobility by using only areference signal supported by different base stations (i.e., a servingbase station and a target base station).

In addition, the base station may transmit a certain signal andparticipate (config.) in the corresponding determination to allow theterminal to select a specific type of reference signal.

FIGS. 18 and 19 show examples of a signal transmitted to a terminal by abase station and utilized to calculate a cell measured value accordingto an embodiment of the disclosure.

Referring to FIG. 18 , the signal transmitted to the terminal by thebase station may include a preferred reference signal type 1810 andinformation 1820 about a method for determining a cell representativevalue by using the reference signal. For example, this information 1820may include the number of beams (e.g., 1, K, all) to be used fordetermining a cell representative value, an index indicating a methodfor selecting a beam (e.g., whether to select an arbitrary beam or thebest beam), the type of an equation for calculating a cellrepresentative value (e.g., sum, average, and weighted sum withdifferent weights for different K beams), and the like.

The base station and the terminal may know in advance an index regardinga method for calculating a cell representative value as shown in Table 9below. In case of weighted summation, the base station should transmitrespective weights as shown in FIG. 20 .

TABLE 9 Derivation index in a base station transmission signal formeasurement of a cell representative value by a terminal (Derivationindex for cell level measurement) Derivation Method Index Summation 0Average 1 Weighted summation 2

Referring to FIG. 19 , alternatively, the signal transmitted to theterminal by the base station may include indexes 1910, 1920, and 1930 ofpreferred reference signal types and information 1940, 1950, and 1960about methods for determining a cell representative value by using thereference signal. For example, this information 1820 may include thenumber of beams (e.g., 1, K, all) to be used for determining a cellrepresentative value, an index indicating a method for selecting a beam(e.g., whether to select an arbitrary beam or the best beam), the typeof an equation for calculating a cell representative value (e.g., sum,average, and weighted sum with different weights for different K beams),and the like. The base station and the terminal may know in advance anindex of each reference signal type as shown in Table 10 below.

TABLE 10 Reference signal index for measurement of a cell representativevalue by a terminal the UE (RS index for cell level measurement) Kind ofRS Index Beam based additional RS 0 (could be BRS, MRS, CSI-RS, —)Synchronization Signal 1 DM-RS for PBCH 2

This information may be included as an information element in part of acertain RRC message, as a media access control (MAC) control element(CE) in part of a certain MAC message, or as a physical (PHY) element inpart of a certain PHY message.

FIG. 20 is a diagram illustrating an example of a signal includingweights transmitted to a terminal by a base station according to anembodiment of the disclosure.

Referring to FIG. 20 , the signal may include a preferred referencesignal type 2010, the number of beams 2020 to be used, and informationabout a method 2030 for determining a cell representative value. Also,any information described above in FIGS. 18 and 19 may be furtherincluded. In addition, if the method for determining a cellrepresentative value is weighted average or weighted summation, the basestation may transmit respective weights 2040 to the terminal.

FIG. 21 is a diagram illustrating a method for a terminal to calculate acell representative value for each RS from different RSs through aseparate procedure according to an embodiment of the disclosure.

Referring to FIG. 21 , the terminal may calculate cell representativevalues for respective RSs through separate procedures without mixing orselecting different beam measurement information received from differenttype RSs. In this case, the filtering and cell representative valuecalculation equations for different type RSs may be the same ordifferent.

If different filtering and cell representative value calculationequations are used for different type RSs, the base station may transmitthis information to the terminal to perform filtering and cellrepresentative value calculation.

FIG. 22 is a diagram illustrating a method for controlling a change ofmobility by using different types of reference signals according to anembodiment of the disclosure.

Referring to FIG. 22 , a UE (i.e., a terminal) may report a measurementresult of a reference signal type 1 at operation S2210.

Based on the measurement result, a gNB (i.e., a base station) maydetermine at operation S2220 whether transmission of a reference signaltype 2 is needed.

If it is determined that transmission of the reference signal type 2 isrequired, the gNB may transmit the reference signal type 2 to the UE atoperation S2230. Then, the gNB may receive a measurement result of thereference signal type 2 at operation S2240.

At operation S2250, the gNB determines whether a mobility change(handover, etc.) is necessary, based on the measurement result. Ifnecessary, the gNB may request or instruct the mobility change atoperation S2260.

At this time, the gNB may determine a cell representative value by usingvalues measured through different types of reference signals accordingto a method described above or to be described below, and thendetermine, by using the representative value, whether the mobilitychange is necessary.

FIGS. 23 to 28 show various embodiments of selecting different numbers(N1, N2, . . . , Nk) of beam measurement signals for different types ofreference signals (RSs) in the order of best performance and thenderiving a cell representative value by multiplying the selected signalsby different weights according to various embodiments of the presentdisclosure. This weight may be a positive number or a negative number,and may be greater or smaller than 1.

Referring to FIG. 23 , a method is illustrated for calculatingrepresentative values 2310 and 2320 for respective RSs through separateprocedures for different types of RSs and then determining one cellrepresentative value by using the above representative values. Referringto FIG. 23 , the UE may determine the cell representative value bymultiplying a measured value determined for each RS by a weight.

Referring to FIG. 24 a method is illustrated for multiplying each beammeasurement signal by the same weight 2410 with respect to the same typeof RSs and then determining a cell representative value 2420. On theother hand, with respect to different types of RSs, different weights(weight 1 and weight 2) may be applied. However, the weight 1 and theweight 2 may be the same value.

Referring to FIG. 25 a method is illustrated for selecting a specificnumber of beam measurement signals with respect to different types ofRSs, multiplying a representative value for each RS by a weight, andthereby deriving a cell representative value. Referring to FIG. 25 , theUE may select N1 best beams 2510 and N2 best beams 2520 for additionalRSs and idle mode RSs, respectively, and then determine representativevalues 2530 and 2540 for the respective RSs. Also, the UE may calculatea cell representative value 2550 by applying a weight to therepresentative value for each RS.

Referring to FIG. 26 a method is illustrated for selecting a specificnumber of beam measurement signals with respect to different types ofRSs, calculating a representative value for each RS type by multiplyingeach selected beam measurement signal by a weight, and deriving a cellrepresentative value by multiplying the representative value for each RStype by a weight. In this case, the weights applied to the respectivebeam measurement signals may be different from or equal to each other.

Referring to FIG. 26 , the UE selects N1 best beams 2610 and N2 bestbeams 2620 for additional RSs and idle mode RSs, respectively,multiplies each selected beam measurement signal by a correspondingweight 2630 or 2640, and determines a representative value 2650 or 2660for each RS type. Then, the UE may calculate a cell representative value2670 by applying a weight to the representative value for each RS type.

FIG. 27 shows another method for selecting a different number of beammeasurement signals with respect to different types of RSs and thenderiving a cell representative value by multiplying the selected signalsby different weights according to an embodiment of the disclosure.

Referring to FIG. 27 , the UE may select N1 best beams 2710 and N2 bestbeams 2720 for additional RSs and idle mode RSs, respectively, andmultiply each selected beam measurement signal by a corresponding weight2730 or 2740. Then, using the result, the UE may calculate a cellrepresentative value 2770. In this case, the weights applied to therespective beam measurement signals may be different from or equal toeach other.

FIG. 28 is a diagram illustrating a method for deriving a cellrepresentative value by multiplying all beam measurement signals bydifferent weights with respect to different types of RSs according to anembodiment of the disclosure.

Referring to FIG. 28 , the UE may multiply each of all beam measurementsignals for additional RSs and idle mode RSs by corresponding weight2810 or 2820. Then, using the result, the UE may calculate a cellrepresentative value 2830. In this case, the weights applied to therespective beam measurement signals may be different from or equal toeach other.

FIG. 29 is a diagram illustrating a method for controlling a mobilitychange by using different types of reference signals according to anembodiment of the disclosure.

Referring to FIG. 29 , the UE may receive a reference signal type 1 fromeach of the first gNB and the second gNB base station at operationsS2910 and S2920, and then report a measurement result to the first gNBat operation S2930.

Based on the measurement result, the first gNB may determines atoperation S2940 whether transmission of a reference signal type 2 isrequired. If it is determined that it is necessary, the first gNB mayrequest the reference signal type 2 to the second gNB at operationS2950.

Accordingly, the second gNB may recognize the necessity of transmissionof the reference signal type 2 at operation S2960. Then, each of thefirst gNB and the second gNB may transmit the reference signal type 2 tothe UE at operations S2970 and S2975. Therefore, the UE may transmit ameasurement result for the reference signal type 2 to the first gNB atoperation S2980. Then, at operation S2985, the first gNB may determine,based on the measurement result, whether it is necessary to change themobility. If necessary, the first gNB may transmit a request orinstruction for the mobility change to the UE at operation S2990.

<Measurement Report Triggering Events Using Measured Values of DifferentRSs>

Event Description [event NR1] NR1 Serving becomes better than threshold(Entering condition) NR1-1-1) Ms(IDLE mode RS) − Hys1 > Threshold1NR1-1-2) Ms(Additional RS) − Hys2 > Threshold2 NR1-1-3) (Ms(IDLE modeRS) − Hys1 > Threshold1) && (Ms(Additional RS) − Hys2 > Threshold2)NR1-1-4) MS(IDLE mode RS) + Ms(Additional RS) − Hys3 > Threshold3(Leaving condition) NR1-2-1) Ms(IDLE mode RS) + Hys1 < Threshold1NR1-2-2) Ms(Additional RS) + Hys2 < Threshold2 NR1-2-3) (Ms(IDLE modeRS) + Hys1 < Threshold1) && (Ms(Additional RS) + Hys2 < Threshold2)NR1-2-4) Ms(IDLE mode RS) + Ms(Additional RS) + Hys3 < Threshold3 #Ms(IDLE mode RS) is the measurement result of the serving cell derivedfrom IDLE mode RS, not taking into account any offsets, # Ms(AdditionalRS) is the measurement result of the serving cell derived fromadditional RS, not taking into account any offsets, # Hys1, Hys2, andHys3 are the hysteresis parameter for this event (i.e. hysteresis asdefined within reportConfigEUTRA for this event), # Threshold1,Threshold2, and Threshold3 are the threshold parameter for this event(i.e. a1-Threshold1, a1-Threshold2, and a1-Threshold3 as defined withinreportConfigEUTRA for this event). # Ms(IDLE mode RS) is expressed indBm in case of RSRP, or in dB in case of RSRQ and RS-SINR, #Ms(Additional RS) is expressed in dBm in case of RSRP, or in dB in caseof RSRQ and RS-SINR, # Hys1, Hys2, and Hys3 are expressed in dB, #Threshold1, Threshold2, and Threshold3 are expressed in the same unit asMs. [event NR2] NR2 Serving becomes worse than threshold (Enteringcondition) NR2-1-1) Ms(IDLE mode RS) + Hys1 < Threshold1 NR2-1-2)Ms(Additional RS) + Hys2 < Threshold2 NR2-1-3) (Ms(IDLE mode RS) + Hys1< Threshold1) && (Ms(Additional RS) + Hys2 < Threshold2) NR2-1-4)Ms(IDLE mode RS) + Ms(Additional RS) + Hys3 < Threshold3  (Leavingcondition) NR2-2-1) Ms(IDLE mode RS) − Hys1 > Threshold1 NR2-2-2)Ms(Additional RS) − Hys2 > Threshold2 NR2-2-3) (Ms(IDLE mode RS) −Hys1 > Threshold1) && (Ms(Additional RS) − Hys2 > Threshold2) NR2-2-4)Ms(IDLE mode RS) + Ms(Additional RS) − Hys3 > Threshold3 # Ms(IDLE modeRS) is the measurement result of the serving cell derived from IDLE modeRS, not taking into account any offsets, # Ms(Additional RS) is themeasurement result of the serving cell derived from additional RS, nottaking into account any offsets, # Hys1, Hys2, and Hys3 are thehysteresis parameter for this event (i.e. hysteresis as defined withinreportConfigEUTRA for this event), # Threshold1, Threshold2, andThreshold3 are the threshold parameter for this event (i.e.a1-Threshold1, a1-Threshold2, and a1-Threshold3 as defined withinreportConfigEUTRA for this event). # Ms(IDLE mode RS) is expressed indBm in case of RSRP, or in dB in case of RSRQ and RS-SINR, #Ms(Additional RS) is expressed in dBm in case of RSRP, or in dB in caseof RSRQ and RS-SINR, # Hys1, Hys2, and Hys3 are expressed in dB, #Threshold1, Threshold2, and Threshold3 are expressed in the same unit asMs.

The following table divided into several pages shows the description ofevent NR3.

[event NR3] NR3 Neighbour becomes offset better than PCell/ PSCell(Entering condition) NR3-1-1) Mn(IDLE mode RS) + Ofn1 + Ocn1 − Hys1 >Mp(IDLE mode RS) + Ofp1 + Ocp1 + Off1 NR3-1-2) Mn(Additional RS) +Ofn2 + Ocn2 − Hys2 > Mp(Additional RS) + Ofp2 + Ocp2 + Off2 NR3-1-3)(Mn(IDLE mode RS) + Ofn1 + Ocn1 − Hys1 > Mp(IDLE mode RS) + Ofp1 +Ocp1 + Off1) && (Mn(Additional RS) + Ofn2 + Ocn2 − Hys2 > Mp(AdditionalRS) + Ofp2 + Ocp2 + Off2) NR3-1-4) Mn(IDLE mode RS) + Mn(AdditionalRS) + Ofn3 + Ocn3 − Hys3 > Mp(IDLE mode RS) + Mp(Additional RS) + Ofp3 +Ocp3 + Off3 (Leaving condition) NR3-2-1) Mn(IDLE mode RS) + Ofn1 +Ocn1 + Hys1 < Mp(IDLE mode RS) + Ofp1 + Ocp1 + Off1 NR3-2-2)Mn(Additional RS) + Ofn2 + Ocn2 + Hys2 < Mp(Additional RS) + Ofp2 +Ocp2 + Off2 NR3-2-3) (Mn(IDLE mode RS) + Ofn1 + Ocn1 + Hys1 < Mp(IDLEmode RS) + Ofp1 + Ocp1 + Off1) && (Mn(Additional RS) + Ofn2 + Ocn2 +Hys2 < Mp(Additional RS) + Ofp2 + Ocp2 + Off2) NR3-2-4) Mn(IDLE modeRS) + Mn(Additional RS) + Ofn3 + Ocn3 + Hys3 < Mp(IDLE mode RS) +Mp(Additional RS) + Ofp3 + Ocp3 + Off3 # Mn(IDLE mode RS) is themeasurement result of the neighbour cell derived from IDLE mode RS, nottaking into account any offsets, # Mn(Additional RS) is the measurementresult of the neighbour cell derived from additional RS, not taking intoaccount any offsets, # Mp(IDLE mode RS) is the measurement result of thePCell/ PSCell derived from IDLE mode RS, not taking into account anyoffsets, # Mp(Additional RS) is the measurement result of the PCell/PSCell derived from additional RS, not taking into account any offsets.# Hys1, Hys2, and Hys3 are the hysteresis parameter for this event (i.e.hysteresis as defined within reportConfigEUTRA for this event), # Ofn1,Ofn2, and Ofn3 are the frequency specific offset of the frequency of theneighbour cell (i.e. offsetFreq as defined within measObjectEUTRAcorresponding to the frequency of the neighbour cell). # Ocn1, Ocn2, andOcn3 are the cell specific offset of the neighbour cell (i.e.cellIndividualOffset as defined within measObjectEUTRA corresponding tothe frequency of the neighbour cell), and set to zero if not configuredfor the neighbour cell. # Ofp1, Ofp2, and Ofp3 are the frequencyspecific offset of the frequency of the PCell/ PSCell (i.e. offsetFreqas defined within measObjectEUTRA corresponding to the frequency of thePCell/ PSCell). #Ocp1, Ocp2, and Ocp3 are the cell specific offset ofthe PCell/ PSCell (i.e. cellIndividualOffset as defined withinmeasObjectEUTRA corresponding to the frequency of the PCell/ PSCell),and is set to zero if not configured for the PCell/ PSCell. #Off1, Off2,and Off3 are the offset parameter for this event (i.e. a3-Offset asdefined within reportConfigEUTRA for this event). # Mn( ) and Mp( ) areexpressed in dBm in case of RSRP, or in dB in case of RSRQ and RS-SINR,# Hys1, Hys2, and Hys3 are expressed in dB, # Ofn, Ocn, Ofp, Ocp, Offare expressed in dB. [event NR4] NR4 Neighbour becomes better thanthreshold (Entering condition) NR4-1-1) Mn(IDLE mode RS) + Ofn1 + Ocn1 −Hys1 > Threshold1 NR4-1-2) Mn(Additional RS) + Ofn2 + Ocn1 − Hys2 >Threshold2 MR4-1-3) (Mn(IDLE mode RS) + Ofn1 + Ocn1 − Hys1 > Threshold1)&& (Mn(Additional RS) + Ofn2 + Ocn2 − Hys2 > Threshold2) NR4-1-4)Mn(IDLE mode RS) + Mn(Additional RS) + Ofn3 + Ocn3 − Hys3 > Threshold3(Leaving condition) NR4-2-1) Mn(IDLE mode RS) + Ofn1 + Ocn1 + Hys1 <Threshold1 NR4-2-2) Mn(Additional RS) + Ofn2 + Ocn2 + Hys2 < Threshold2NR4-2-3) (Mn(IDLE mode RS) + Ofn1 + Ocn1 + Hys1 < Threshold1) &&(Mn(Additional RS) + Ofn2 + Ocn2 + Hys2 < Threshold2) NR4-2-4) Mn(IDLEmode RS) + Mn(Additional RS) + Ofn3 + Ocn3 + Hys3 < Threshold3 # Mn(IDLEmode RS) is the measurement result of the neighbour cell derived fromIDLE mode RS, not taking into account any offsets. # Mn(Additional RS)is the measurement result of the neighbour cell derived from additionalRS, not taking into account any offsets, # Hys1, Hys2, and Hys3 are thehysteresis parameter for this event (i.e. hysteresis as defined withinreportConfigEUTRA for this event), # Ofn1, Ofn2, and Ofn3 are thefrequency specific offset of the frequency of the neighbour cell (i.e.offsetFreq as defined within measObjectEUTRA corresponding to thefrequency of the neighbour cell). # Ocn1, Ocn2 and Ocn3 are the cellspecific offset of the neighbour cell (i.e. cellIndividualOffset asdefined within measObjectEUTRA corresponding to the frequency of theneighbour cell), and set to zero if not configured for the neighbourcell. # Threshold1, Threshold2, and Threshold3 are the thresholdparameter for this event (i.e. a1-Threshold1, a1-Threshold2, anda1-Threshold3 as defined within reportConfigEUTRA for this event). # Mn() are expressed in dBm in case of RSRP, or in dB in case of RSRQ andRS-SINR, # Hys1, Hys2, and Hys3 are expressed in dB, # Ofn, Ocn, Ofp,Ocp, Off are expressed in dB. # Threshold1, Threshold2, and Threshold3are expressed in the same unit as Mn( )

The following table divided into several pages shows the description ofevent NR5.

[event NR5] NR5 PCell/ PSCell becomes worse than thresholdA andneighbour becomes better than thresholdB 1 > consider the enteringcondition for this event to be satisfied when both condition  5-1-X andcondition 5-2-X, as specified below, are fulfilled; 1 > consider theleaving condition for this event to be satisfied when condition 5-3-X or condition 5-4-X, i.e. at least one of the two, as specified below,is fulfilled; (Entering condition 1) NR5-1-1) Mp(IDLE mode RS) + HysA1 <ThresholdA1 NR5-1-2) Mp(Additional RS) + HysA2 < ThresholdA2 NR5-1-3)(Mp(IDLE mode RS) + HysA1 < ThresholdA1) && (Mp(Addttional RS) + HysA2 <ThresholdA2) NR5-1-4) Mp(IDLE mode RS) + Mp(Additional RS) + HysA3 <ThresholdA3 (Entering condition 2) NR5-2-1) Mn(IDLE mode RS) + Ofn1 +Ocn1 − HysB1 > ThresholdB1 NR5-2-2) Mn(Additional RS) + Ofn2 + Ocn2 −HysB2 > ThresholdB2 NR5-2-3) (Mn(IDLE mode RS) + Ofn1 + Ocn1 − HysB1 >ThresholdB1) && (Mn(Additional RS) + Ofn2 + Ocn2 − HysB2 > ThresholdB2)NR5-2-4) Mn(IDLE mode RS) + Mn(Additional RS) + Ofn3 + Ocn3 − Hys3 >ThresholdB3 (Leaving condition 1) NR5-3-1) Mp(IDLE mode RS) − HysA1 >ThresholdA1 NR5-3-2) Mp(Additional RS) − HysA2 > thresholdA2 NR5-3-3)(Mp(IDLE mode RS) − HysA1 > ThresholdA1) && Mp(Additional RS) − HysA2 >ThresholdA2) NR5-3-4) Mp(IDLE mode RS) + Mp(Additional RS) − HysA3 >ThresholdA3 (Leaving condition 2) NR5-4-1) Mn(IDLE mode RS) + Ofn1 +Ocn1 + HysB1 < ThresholdB1 NR5-4-2) Mn(Additional RS) + Ofn1 + Ocn2 +HysB2 < ThresholdB2 NR5-4-3) (Mn(IDLE mode RS) + Ofn1 + Ocn1 + HysB1 <ThresholdB1) && (Mn(Additional RS) + Ofn2 + Ocn2 + HysB2 < ThresholdB2)NR5-4-4) Mn(IDLE mode RS) + Mn(Additional RS) + Ofn3 + Ocn3 + HysB3 <ThresholdB3 # Mn(IDLE mode RS) is the measurement result of theneighbour cell derived from IDLE mode RS, not taking into account anyoffsets, # Mn(Additional RS) is the measurement result of the neighbourcell derived from additional RS, not taking into account any offsets, #Mp(IDLE mode RS) is the measurement result of the PCell/ PSCell derivedfrom IDLE mode RS, not taking into account any offsets, # Mp(AdditionalRS) is the measurement result of the PCell/ PSCell derived fromadditional RS, not taking into account any offsets, # HysA1, HysA2,HysA3, HysB1, HysB2, and HysB3 are the hysteresis parameter for thisevent (i.e. hysteresis as defined within reportConfigEUTRA for thisevent), # Ofn1, Ofn2, and Ofn3 are the frequency specific offset of thefrequency of the neighbour cell (i.e. offsetFreq as defined withinmeasObjectEUTRA corresponding to the frequency of the neighbour cell). #Ocn1, Ocn2, and Ocn3 are the cell specific offset of the neighbour cell(i.e. cellIndividualOffset defined within measObjectEUTRA correspondingto the frequency of the neighbour cell), and set to zero if notconfigured for the neighbour cell. # Ofp1, Ofp2, and Ofp3 are thefrequency specific offset of the frequency of the PCell/ PSCell (i.e.offsetFreq as defined within measObjectEUTRA corresponding to thefrequency of the PCell/ PSCell). #Ocp1, Ocp2, and Ocp3 are the cellspecific offset of the PCell/ PSCell (i.e. cellIndividualOffset asdefined within measObjectEUTRA corresponding to the frequency of thePCell/ PSCell), and is set to zero if not configured for the PCell/PSCell. #Off1, Off2, and Off3 are the offset parameter for this event(i.e. a3-Offset as defined within reportConfigEUTRA for this event). #Mn( ) and MP( ) are expressed in dBm in case of RSRP, or in dB in caseof RSRQ and RS-SINR, # HysA1, HysA2, HysA3, HysB1, HysB2, and HysB3 areexpressed in dB, # Ofn, Ocn, Ofp, Ocp, Off are expressed in dB.

The following table divided into several pages shows the description ofevent NR6.

[event NR6] NR6 Neighbour becomes offset better than SCell (Enteringcondition) NR3-1-1) Mn(IDLE mode RS) + Ocn1 − Hys1 > Ms(IDLE mode RS) +Ocs1 + Off1 NR3-1-2) Mn(Additional RS) + Ocn2 − Hys2 > Ms(AdditionalRS) + Ocs2 + Off2 NR3-1-3) (Mn(IDLE mode RS) + Ocn1 − Hys1 > Ms(IDLEmode RS) + Ocs1 + Off1) && (Mn(Additional RS) + Ocn2 − Hys2 >Ms(Additional RS) + Ocs2 + Off2) + NR3-1-4) Mn(IDLE mode RS) +Mn(Additional RS) + Ocn3 − Hys3 > Ms(IDLE mode RS) Ms(Additional RS) +Ocs3 + Off3 (Leaving condition) NR3-2-1) Mn(IDLE mode RS) + Ocn1 + Hys1< Ms(IDLE mode RS) + Ocs1 + Off1 NR3-2-2) Mn(Additional RS) + Ocn2 +Hys2 < Ms(Additional RS) + Ocs2 + Off2 NR3-2-3) Mn(IDLE mode RS) +Ocn1 + Hys1 < Ms(IDLE mode RS) + Ocs1 + Off1) && (Mn(Additional RS) +Ocn2 + Hys2 < Ms(Additional RS) + Ocs2 + Off2) NR3-2-4) Mn(IDLE modeRS) + Mn(Additional RS) + Ocn3 + Hys3 < Ms(IDLE mode RS) + Ms(AdditionalRS) + Ocs3 + Off3 # Mn(IDLE mode RS) is the measurement result of theneighbour cell derived from IDLE mode RS, not taking into account anyoffsets, # Mn(Additional RS) is the measurement results of the neighbourcell derived from additional RS, not taking into account any offsets, #Ms(IDLE mode RS) is the measurement result of the serving cell derivedfrom IDLE mode RS, not taking into account any offsets, # Ms(AdditionalRS) is the measurement result of the serving cell derived fromadditional RS, not taking into account any offsets, # Hys1, Hys2, andHys3 are the hysteresis parameter for this event (i.e. hysteresis asdefined within reportConfigEUTRA for this event), # Ocn1, Ocn2, and Ocn3are the cell specific offset of the neighbour cell (i.e.cellIndividualOffset as defined within measObjectEUTRA corresponding tothe frequency of the neighbour cell), and set to zero if not configuredfor the neighbour cell. #Ocs1, Ocs2, and Ocs3 are the cell specificoffset of the serving cell (i.e. cellIndividualOffset as defined withinmeasObjectEUTRA corresponding to the frequency of the PCell/ PSCell),and is set to zero if not configured for the PCell/ PSCell. #Off1, Off2,and Off3 are the offset parameter for this event (i.e. a3-Offset asdefined within reportConfigEUTRA event). # Mn( ) and Ms( ) are expressedin dBm in case of RSRP, or in dB in case of RSRQ and RS-SINR, # Hys1,Hys2, and Hys3 are expressed in dB, # Ocn, Ocs, Off are expressed in dB.

The following table divided into several pages shows the description ofevent NR7.

[event NR7] NR7 Neighbour becomes offset better than PCell/ PSCell,while there are more than N beams above threshold in that neighbour cell1> consider the entering condition for this event to be satisfied whenboth condition 7-1-X and condition 7-2-X, as specified below, arefulfilled; 1> consider the leaving condition for this event to besatisfied when condition 7-3-X or condition 7-4-X, i.e. at least one ofthe two, as specified below, is fulfilled; (Entering condition 1)NR7-1-1) Mn(IDLE mode RS) + Ofn1 + Ocn1 − Hys1 > Mp(IDLE mode RS) +Ofp1 + Ocp1 + Off1 NR7-1-2) Mn(Additional RS) + Ofn2 + Ocn2 − Hys2 >Mp(Additional RS) + Ofp2 + Ocp2 + Off2 NR7-1-3) (Mn(IDLE mode RS) +Ofn1 + Ocn1 − Hys1 > Mp(IDLE mode RS) + Ofp1 + Ocp1 + Off1) &&(Mn(Additional RS) + Ofn2 + Ocn2 − Hys2 > Mp(Addttional RS) + Ofp2 +Ocp2 + Off2) NR7-1-4) Mn(IDLE mode RS) + Mn(Additional RS) + Ofn3 + Ocn3− Hys3 > Mp(IDLE mode RS) + Mp(Additional RS) + Ofp3 + Ocp3 + Off3(Entering condition 2) NR7-2-1) # of beams satisfy (MBn(IDLE mode RS) >Threshold1) > N1, NR7-2-2) # of beams satisfy (MBn(Additional RS) >Threshold2) > N2, NR7-2-3) # of beams satisfy ((MBn(IDLE mode RS) >Threshold1) or (MBn(Additional RS) > Threshold2) ) > N3, (Leavingcondition 1) NR7-3-1) Mn(IDLE mode RS) + Ofn1 + Ocn1 + Hys1 < Mp(IDLEmode RS) + Ofp1 + Ocp1 + Off1 NR7-3-2) Mn(Additional RS) + Ofn2 + Ocn2 +Hys2 < Mp(Additional RS) + Ofp2 + Ocp2 + Off2 NR7-3-3) (Mn(IDLE modeRS) + Ofn1 + Ocn1 + Hys1 < Mp(IDLE mode RS) + Ofp1 + Ocp1 + Off1) &&(Mn(Additional RS) + Ofn2 + Ocn2 + Hys2 < Mp(Additional RS) + Ofp2 +Ocp2 + Off2) NR7-3-4) Mn(IDLE mode RS) + Mn(Additional RS) + Ofn3 +Ocn3 + Hys3 < Mp(IDLE mode RS) + Mp(Additional RS) + Ofp3 + Ocp3 +Off3 - (Leaving condition 2) NR7-4-1) # of beams satisfy (MBn(IDLE modeRS) > Threshold1) < N1, NR7-4-2) # of beams satisfy (MBn(AdditionalRS) > Threshold2) < N2, NR7-4-3) # of beams satisfy ( (MBn(IDLE modeRS) > Threshold1) or | (MBn(Additional RS) > Threshold2) ) < N3, #Mn(IDLE mode RS) is the measurement result of the neighbor cell derivedfrom IDLE mode RS, not taking into account any offsets. # Mn(AdditionalRS) is the measurement result of the neighbor cell derived fromadditional RS, not taking into account any offsets. # MBn(IDLE mode RS)is the measurement result of a beam of the neighbor cell derived fromIDLE mode RS, not taking into account any offsets. # MBn(Additional RS)is the measurement result of a beam of the neighbour cell derived fromadditional RS, not tkaing into account any offsets. # Mp(IDLE mode RS)is the measurement result of the PCell/ PSCell derived from IDLE modeRS, not taking into account any offsets. # Mp(Additional RS) is themeasurement result of PCell/ PSCell deived from additional RS, nottaking into account any offsets. # Hys1, Hys2, and Hys3 are thehysteresis parameter for this event (i.e. hysteresis as defined withinreportConfigEUTRA for this event). # Ofn1, Ofn2, and Ofn3 are thefrequency specific offset of the frequency of the neighbor cell (i.e.offsetFreq as defined within measObjectEUTRA corresponding to thefrequency of the neighbor cell). # Ocn1, Ocn2, and Ocn3 are the cellspecific offset of the neighbor cell (i.e. cellindividualOffset asdefined within measObjectEUTRA corresponding to the frequency of theneighbor cell), and set to zero is not configured for the neighbor cell.# Ofp1, Ofp2, and Ofp3 are the frequency specific offset of thefrequency of the PCell/ PSCell (i.e offsetFreq as defined withinmeasObjectEUTRA corresponding to the frequency of the PCell/ PSCell).#Ocp1, Ocp2, and Ocp3 are the cell specific offset of the PCell/ PSCell(i.e. cellindividualOffset as defined within measObjectEUTRAcorresponding to the frequency of the PCell/ PSCell), and is set to zeroif not configured for the PCell/ PSCell. #Off1, Off2, and Off3 are theoffset parameter for this event (i.e. a3-Offset as defined withinreportConfigEUTRA for this event). # N1, N2, and N3 are the requirednumber of beams which satisfies the threshold required # Threshold1,Threshold2, and Threshold3 are the threshold parameter for this event(i.e. a1- Threshold1, a1-Threshold2 and a1-Threshold3 as defined withinreportConfigEUTRA for this event). # Mn( ) and Mp( ) are expressed indBm in case of RSRP, or in dB in case of RSRQ and RS-SINR. # Hys1, Hys2,and Hys3 are expressed in dB. # Ofn, Ocn, Ofp, Ocp, Off are expressed indB. # Threshold1, Threshold2, and Threshold3 are expressed in the sameunit as Ms.

FIG. 30 is a diagram illustrating a terminal according to an embodimentof the disclosure.

Referring to FIG. 30 , the terminal 3000 may include a transceiver 3010for transmitting and receiving a signal, and a controller 3030.

The terminal 3000 may transmit and/or receive signals, information,messages, and the like through the transceiver 3010. For example, whendefining a controller in the specification, it may be stated that “thecontroller may be a circuit, an application-specific integrated circuitor at least one processor.”

The controller 3030 may control the overall operation of the terminal3000. The controller 3030 may include at least one processor. Thecontroller 3030 may control the operation of the terminal described inembodiments of the disclosure. For example, the controller 3030 maycontrol a signal flow in the above-described flow diagram.

FIG. 31 is a diagram illustrating a base station according to anembodiment of the disclosure.

Referring to FIG. 31 , the base station 3100 may include a transceiver3110 for transmitting and receiving a signal, and a controller 3130. Forexample, when defining a controller in the specification, it may bestated that “the controller may be a circuit, an application-specificintegrated circuit or at least one processor.”

The base station 3100 may transmit and/or receive signals, information,messages, and the like through the transceiver 3110.

The controller 3130 may control the overall operation of the basestation 3100. The controller 3130 may include at least one processor.The controller 3130 may control the operation of the base stationdescribed in embodiments of the disclosure. For example, the controller3130 may control a signal flow in the above-described flow diagram.

Third Embodiment

Meanwhile, in a situation where a reference signal (hereinafter referredto as an idle mode RS) for both an idle mode UE and a connected mode UEand a reference signal (hereinafter referred to as a connected mode RS)for only the connected mode UE coexist, a UE may perform an RRMmeasurement through the idle mode RS and then (a) request the connectedmode RS at an appropriate time or (b) report a connected mode RSmeasurement result to a gNB when the gNB transmits the connected mode RSat an appropriate time. The disclosure provides a related operation.

FIG. 32 is a flow diagram illustrating an initial access operationaccording to an embodiment of the disclosure.

Referring to FIG. 32 , in an RRC connection establishment procedure, thedisclosure proposes a method about (a) when the UE requests the gNB totransmit the connected mode RS, (b) when the gNB transmits the connectedmode RS, and (c) when the gNB allocates a resource for the connectedmode RS measurement report of the UE. This operation proposed by thedisclosure is based on FIG. 32 .

That is, based on a random access procedure and an RRC connectionprocedure shown in operations S3210 to S3260 of FIG. 32 , the UE mayrequest transmission of the connected mode RS, and the gNB may transmitthe connected mode RS and allocate a resource for the connected mode RSmeasurement report of the UE. Details will be described below.

<Request for Connected Mode RS>

The UE may request the gNB to transmit a connected mode RS throughpreamble classification when transmitting a random access preamble atoperation S3220.

For this, random access preambles are classified into two groups. If theUE transmits the random access preamble belonging to one group, the gNBunderstands a request for the connected mode RS. If the UE transmits therandom access preamble belonging to the other group, the gNB understandsno request for the connected mode RS.

In case of requesting the connected mode RS, the UE continuouslyperforms blind decoding for physical downlink control channel (PDCCH) toknow allocation information about a resource for transmission of theconnected mode RS by the gNB and a resource for transmission of arelated measurement result report by the UE.

Alternatively, when transmitting an RRC connection request message atoperation S3240, the UE may set a bit indicating a request fortransmission of the connected mode RS to 1 in the above message so as torequest the gNB to transmit the connected mode RS.

If the corresponding bit is set to 0, the gNB understands that the UEdoes not request the transmission of the connected mode RS.

Alternatively, when transmitting an RRC connection setup completemessage at operation S3260, the UE may set a bit indicating a requestfor transmission of the connected mode RS to 1 in the above message soas to request the gNB to transmit the connected mode RS.

<Allocation of Connected Mode RS Resource>

When transmitting a random access response message at operation S3230,the gNB allocates a resource for transmission of the connected mode RSin the above message.

Alternatively, when transmitting an RRC connection setup message atoperation S3250, the gNB allocates a resource for transmission of theconnected mode RS in the above message.

Here, the allocated resource is a time/frequency resource and may beexpressed as a resource block index or the like.

Alternatively, the gNB allocates a resource for transmission of theconnected mode RS through a separate signal, for example, PDCCH downlinkcontrol information (DCI).

<Allocation of Connected Mode RS Measurement Result Feedback Resource>

When transmitting the random access response message at operation S3230,the gNB allocates a resource for reporting the connected mode RSmeasurement result in the above message.

Alternatively, when transmitting the RRC connection setup message atoperation S3250, the gNB allocates a resource for reporting theconnected mode RS measurement result in the above message.

Alternatively, the gNB allocates a resource for reporting the connectedmode RS measurement result through a separate signal, for example, PDCCHDCI.

<Feedback of Connected Mode RS Measurement Result>

When transmitting the RRC connection request message at operation S3240,the UE may insert information about the connected mode RS measurementresult in the above message.

Here, the connected mode RS measurement result includes N beam indexeswith the highest signal strength and corresponding signal strengths(RSRP or RSRQ) after the connected mode RS measurement. Here, N may beset by the gNB through an RRC message or the like.

Alternatively, when transmitting the RRC connection setup completemessage at operation S3260, the UE may insert the connected mode RSmeasurement result information in the above message.

Alternatively, the UE transmits the connected mode RS measurement resultinformation to the gNB through a separate signal, for example, aphysical uplink control channel (PUCCH), a physical uplink sharedchannel (PUSCH), or the like.

FIG. 33 is a flow diagram illustrating a handover operation according toan embodiment of the disclosure.

Referring to FIG. 33 , in a handover procedure, the disclosure proposesa method about (a) when the UE requests the gNB to transmit theconnected mode RS, (b) when the gNB transmits the connected mode RS, and(c) when the gNB allocates a resource for the connected mode RSmeasurement report of the UE. This operation proposed by the disclosureis based on FIG. 33 .

That is, based on the handover procedure shown in S3310 to S3370 of FIG.33 , the UE may request transmission of the connected mode RS, and thegNB may transmit the connected mode RS and allocate a resource for theconnected mode RS measurement report of the UE. Details will bedescribed below.

<Request for Connected Mode RS>

When transmitting a measurement report at operation S3320, the UE sets abit indicating a request for transmission of the connected mode RS to 1in the above message so as to request the gNB to transmit the connectedmode RS. The source gNB and target gNB may initiate handover request andresponse at operation S3330.

Alternatively, when transmitting a random access preamble at operationS3350, the UE requests the gNB to transmit the connected mode RS throughthe preamble classification.

Alternatively, when transmitting an RRC connection reconfigurationcomplete message at operation S3370, the UE sets a bit indicating arequest for transmission of the connected mode RS to 1 in the abovemessage so as to request the gNB to transmit the connected mode RS.

<Allocation of Connected Mode RS Resource>

When transmitting an RRC connection reconfiguration (or mobility controlinformation or handover command) message at operation S3340, the gNBallocates a resource for transmission of the connected mode RS in theabove message.

Alternatively, when transmitting a random access response message atoperation S3360, the gNB allocates a resource for transmission of theconnected mode RS in the above message.

Alternatively, the gNB allocates a resource for transmission of theconnected mode RS through a separate signal, for example, PDCCH DCI.

<Allocation of Connected Mode RS Measurement Result Feedback Resource>

When transmitting the RRC connection reconfiguration (or mobilitycontrol information or handover command) message at operation S3340, thegNB allocates a resource for reporting the connected mode RS measurementresult in the above message.

Alternatively, when transmitting the random access response message atoperation S3360, the gNB allocates a resource for reporting theconnected mode RS operation measurement result in the above message.

Alternatively, the gNB allocates a resource for reporting the connectedmode RS measurement result through a separate signal, for example, PDCCHDCI.

<Feedback of Connected Mode RS Measurement Result>

When transmitting the RRC connection reconfiguration complete message atoperation S3370, the UE inserts the connected mode RS measurement resultinformation in the above message.

Alternatively, the UE transmits the connected mode RS measurement resultinformation to the gNB via a separate signal, for example, PUCCH, PUSCH,or the like.

According to still another example, the operation proposed by thedisclosure is based on FIG. 34 .

FIG. 34 is a flow diagram illustrating an operation according to anembodiment of the disclosure.

Referring to FIG. 34 , at operation S3410 of transmitting an RRCconnection setup request, the UE may request the source gNB to receivean additional RS from the target gNB. The source gNB may transmit arequest for additional RS scheduling to the target gNB at operationS3420, and may receive a response at operation S3430. Accordingly, thesource gNB may transmit a response message to the UE at operation S3440in response to the RRC connection setup request. This message mayinclude scheduling information for the additional RS. At this time, theadditional RS may refer to, for example, a CSI-RS.

Therefore, the UE may receive the RS from the source gNB and the targetgNB at operations S3450 and S3460.

The disclosure considers a system in which the gNB uses asynchronization signal (SS) and a CSI-RS together. Here, the SS mayinclude both a primary synchronization signal (PSS) and a secondarysynchronization signal (SSS). Also, the SS may correspond to acell-specific signal, and the CSI-RS may be a cell-specific signal, aUE-specific signal, or a UE group-specific signal.

The disclosure considers a situation in which the UE initially accessesthe gNB or performs handover from the serving gNB to the target gNB.Also, the disclosure considers a situation where the gNB uses an SSsignal when determining whether the UE performs the initial access orhandover.

In this situation, the disclosure proposes a UE operation of promptlyreceiving allocation of a beam to be used for data communication from aninitially accessed gNB or a handover target gNB. In general, a beam onwhich the SS is transmitted may be a relatively wide beam so as toreduce the time required for beam sweeping or for any other reason.However, a beam for transmission of the CSI-RS or data may be arelatively narrow beam so as to obtain a high beamforming gain.Therefore, the gNB or UE may determine, through the SS transmitted onthe wide beam, whether to perform the initial access or handover, andthe UE may identify the narrow beam to be used for data communication byreceiving the CSI-RS from the accessed gNB or the target gNB.

Also, because there is no idea of when the UE will access the gNB, theSS may be regarded as an always-on signal which is always transmitted.However, the CSI-RS may be an always-on signal or not, depending on theoverhead of time and frequency resources required for transmission. Thedisclosure assumes that the SS is an always-on signal and the CSI-RS isnot an always-on signal. That is, it is assumed that the gNB maydetermine whether to transmit the CSI-RS.

The disclosure assumes that the SS is transmitted through a relativelywide beam and the CSI-RS is transmitted through a relatively narrowbeam. A mapping relationship between the wide beam for SS transmissionand the narrow beam for CSI-RS transmission may be established inaccordance with an antenna pattern of the gNB. The disclosure assumesthat this relationship is established. An example is as shown in thefollowing table.

TABLE 10 SS beam index. CSI-RS beam, index. Mapping between SS beam 1.11, 12, 13, . . . , 1N. and CSI-RS beam. 2. 21. 22, 23, . . . , 2N. 3.31, 32, 33, . . . , 3N. . . . . . . M. M, M2, M3, . . . , MN.

The assumptions considered in the disclosure are as above. However, thedisclosure is not limited to the above and may be generalized in case ofinitial access and handover in a system in which two kinds of RSs areused together.

FIGS. 35 to 41 are flow diagrams illustrating various methods fordetermining a beam to be used for data transmission and reception in ahandover process according to embodiments of the disclosure;

Referring to FIG. 35 , the operation of the disclosure will be describedin a situation where the UE performs handover from the serving gNB tothe target gNB.

1. Referring to FIG. 35 , the serving gNB provides measurementconfiguration information to the UE at operation S3510.

A. Here, the measurement configuration information includes a frequencyto be measured by the UE, a measurement report triggering condition, andthe like.

2. The UE performs measurement, based on the measurement configurationinformation received from the serving gNB.

A. Here, the UE measures the signal strength or quality of the SStransmitted from the serving gNB and the target gNB.

B. In the disclosure, it is assumed that each gNB transmits the SS whilesweeping a plurality of beams directed in different directions.Therefore, the UE may distinguish the SSs transmitted through differentbeams from each other by means of the time and frequency resources usedfor receiving the SSs.

3. If any event that the signal strength of the target gNB is greaterthan the signal strength of the serving gNB by offset is detected atoperation S3520 through a comparison of signal strength, the UEtransmits a measurement report to the serving gNB at operation S3540.

A. In order to transmit the measurement report, the UE may transmit andreceive a scheduling request (SR), a buffer status report (BSR), anuplink (UL) grant, etc. to and from the serving gNB at operation S3530.

B. Although the A3 event is described for example, the same principlemay be applied to other events.

4. When the measurement report is received from the UE, the serving gNBtransmits a handover request to the target gNB at operation S3550 toperform an admission control.

A. If the target gNB can accept the UE, the target gNB transmits anacknowledgement (ACK) for the handover request to the serving gNB atoperation S3550 and provides information required for the UE to accessthe target gNB.

B. This information required for the UE to access the target gNBincludes a dedicated random access preamble (RAP) for the UE tosynchronize uplink with the target gNB, and a necessary C-RNTI for datatransmission/reception between the UE and the target gNB.

5. The serving gNB transmits a handover command to the UE at operationS3560 to provide information necessary for the UE to access the targetgNB.

A. Here, the handover command may include the dedicated RAP and theC-RNTI received from the target gNB through the handover request ACK.

6. Based on information included in the handover command, the UEtransmits a RAP to the target gNB at operation S3570.

A. This is an operation of the UE for controlling transmission (TX)timing and power to perform uplink transmission/reception with thetarget gNB.

7. After receiving the RAP from the UE, the target gNB transmits arandom access response (RAR) to the UE at operation S3580.

A. After receiving the RAP, the target gNB notifies a TX timing andpower adjusting level to the UE through the RAR and, if necessary,requests the UE to transmit the RAP again. After this uplinksynchronization, the target gNB allocates an uplink (UL) grant atoperation S3580 so that the UE can transmit a handover confirm.

8. The UE with the uplink synchronization receives the RAR and transmitsthe handover confirm to the target gNB through the UL grant included inthe RAR at operation S3590.

A. Through this, the UE completes the handover from the serving gNB tothe target gNB.

The above handover operation is designed for a situation where the gNBuses only one RS. This is not suitable for a situation considered in thedisclosure, i.e., a situation where the determination of whether toperform handover is based on the SS transmitted on a wide beam, but theactual data transmission/reception uses a narrow beam. Unsuitableness isbecause the UE fails to determine a narrow beam to be used fortransmitting and receiving data to and from the target gNB despite thecompletion of handover.

In the disclosure, the UE determines whether to perform a handover,through the measurement of the SS transmitted on a wide beam, and thenperforms the measurement of the CSI-RS transmitted on a narrow beamduring the handover procedure so as to find as soon as possible thenarrow beam to be used with the target gNB. Hereinafter, variousembodiments will be described.

[Handover: Proposed 1]

Referring to FIG. 36 , an embodiment of Handover: proposed 1 will bedescribed.

1. The serving gNB provides measurement configuration information to theUE at operation S3610.

2. The UE performs measurement, based on the measurement configurationinformation received from the serving gNB.

A. Here, the UE measures the signal strength or quality of the SStransmitted from the serving gNB and the target gNB.

3. If any event that the signal strength of the target gNB is greaterthan the signal strength of the serving gNB by offset is detected atoperation S3620 through a comparison of signal strength, the UEtransmits a measurement report to the serving gNB at operation S3640.

4. When the measurement report is received from the UE, the serving gNBtransmits a handover request to the target gNB at operation S3650 toperform an admission control.

5. The serving gNB transmits a handover command to the UE at operationS3660 to provide information necessary for the UE to access the targetgNB.

6. Based on information included in the handover command, the UEtransmits a RAP to the target gNB at operation S3670.

A. Here, the target gNB may receive the RAP of the UE while sweeping awide beam used to transmit the SS. In this case, the target gNBmemorizes a wide beam used to receive the RAP of the UE and uses it atthe next step. If the target gNB receives the RAP of the UE through aplurality of wide beams, the target gNB memorizes a wide beam having thehighest signal strength and uses it at the next step.

7. After receiving the RAP from the UE, the target gNB transmits a RARto the UE at operation S3680.

A. After receiving the RAP, the target gNB notifies a TX timing andpower adjusting level to the UE through the RAR and, if necessary,requests the UE to transmit the RAP again. After this uplinksynchronization, the target gNB allocates a UL grant so that the UE cantransmit a handover confirm.

B. Additionally, in the disclosure, the target gNB transmits CSI-RSconfiguration information 3600 together with the RAR to the UE. Thedetails of the CSI-RS configuration information will be described afterthe entire operation description.

8. The target gNB transmits at operation S3690 the CSI-RS through aplurality of narrow beams corresponding to the wide beam used forreceiving the RAP.

9. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the target gNB.

10. The UE with the uplink synchronization receives the RAR andtransmits the handover confirm to the target gNB through the UL grantincluded in the RAR at operation S3691.

A. When transmitting the handover confirm, the UE also transmitsfeedback 3601 of a measurement result for the CSI-RS. At this time, theUE utilizes the UL grant included in the RAR.

B. Through this, the UE completes the handover from the serving gNB tothe target gNB.

11. Based on the CSI-RS feedback of the UE, the target gNB selects anarrow beam to be used by the UE and notifies it to the UE at operationS3692.

In the disclosure, the target gNB provides the CSI-RS configurationinformation to the UE. This is similar to the CSI-RS configurationinformation used in LTE. Additionally, the target gNB needs to informthe UE about beam information for transmission of the CSI-RS.Accordingly, the target gNB may insert the SS beam information used forreceiving the RAP in the CSI-RS configuration information, or may insertthe corresponding CSI-RS beam information. Tables 11 and 12 below showexamples of the CSI-RS configuration information that includes antennaport information, time and frequency resource information, subframeinformation, power information, wide SS beam information used forreception of the RAP, narrow SS beam information to be used fortransmission of the CSI-RS, a CSI-RS transmission period, and a CSI-RSconfiguration valid time.

TABLE 11 CSI-RS-Config The IE CSI-RS-Config is used to specify the CSI(Channel-State Information) reference signal configuration.CSI-RS-Config Information Elements -- ASN1Start CSI-RS-Config-r10 ::=SEQUENCE {  csi-RS-r10 CHOICE {   release NULL,   setup SEQUENCE {   antennaPortsCount-r10 ENUMERATED {an1, an2, an4, an8},   resourceConfig-r10 INTEGER (0..31),    subframeConfig-r10 INTEGER(0..154),    p-C-r10  INTEGER (−8..15),    ssBeamIndex  INTEGER(0..255),    csiBeamSetIndex INTEGER (0..255),    csiBeamPeriodcityINTEGER (0..15),    csiBeamValidTime INTEGER (0..255)   }  }  OPTIONAL,Need ON }

TABLE 12 CSI-RS-Config field descriptions antennaPortsCount. Parametersrepresents the number of antenna ports used for transmission of CSIreference signals where value an1 corresponds to 1 antenna port, an2 to2 antenna ports and so on, see TS 36.211 [21, 6.10.5]. p-C Parameter:P_(C), see TS 36.213 [23, 7.2.5]. The UE shall ignore p-C- r10 ifconfigured with eMIMO-Type unless it is set to beamformed,alternativeCodebookEnabledBeamformed is set to FALSE andcsi-RS-ConfigNZPIdListExt is not configured. resourceConfig Parameter:CSI reference signal configuration, see TS 36.211 [21, table 6.10.5.2-1and 6.10.5.2-2]. subframeConfig Parameter: I_(CSI-RS) see TS 36.211 [21,table 6.10.5.3-1]. ssBeamIndex. The SS beam that gNB receives the RAPfrom UE. A set of CSI-RSs that correspond to the SS will be transmittedby the gNB. csiBeamSetIndex A set of CSI-RS beams that correspond to theSS beam on which gNB receives the RAP from UE. csiBeamPeriodicity Thetransmission period of CSI-RS. Its unit can be subframe, second and soon.  csiBeamValidTime The valid time during which the CSI-RSconfiguration is valid. Its unit can be subframe, second and so on.

Tables 13 to 16 below show methods for determining the CSI-RStransmission period, offset, and resource location in the CSI-RSconfiguration information used in the disclosure. The CSI-RStransmission period, offset, resource location, and power information(p-C) may be determined according to the CSI-RS configurationinformation and the following tables.

TABLE 13 CSI reference signal subframe configurationCSI-RS-SubframeConfig CSI-RS periodicity CSI-RS subframe offsetI_(CSI-RS) T_(CSI-RS) (subframes) Δ_(CSI-RS) (subframes) 0-4 5I_(CSI-RS)  5-14 10 I_(CSI-RS) − 5  15-34 20 I_(CSI-RS) − 15 35-74 40I_(CSI-RS) − 35  75-154 80 I_(CSI-RS) − 75

TABLE 14 Mapping from CSI reference signal configuration to (k′, l′) fornormal cyclic prefix Number of CSI reference signals configured 1 or 2 48 Normal Special Normal Special Normal Special CSI-RS subframe subframesubframe subframe subframe subframe config. (k′, l′) n_(s)′ (k′, l′)n_(s)′ (k′, l′) n_(s)′ (k′, l′) n_(s)′ (k′, l′) n_(s)′ (k′, l′) n_(s)′ 0(9, 5) 0 (9, 5) 0 (9, 5) 0 (9, 5) 0 (9, 5) 0 (9, 5) 0 1 (11, 2)  1 (11,5)  0 (11, 2)  1 (11, 5)  0 (11, 2)  1 (11, 5)  0 2 (9, 2) 1 (9, 2) 1(9, 2) 1 (9, 2) 1 (9, 2) 1 (9, 2) 1 3 (7, 2) 1 (7, 5) 0 (7, 2) 1 (7, 5)0 (7, 2) 1 (7, 5) 0 4 (9, 5) 1 (9, 5) 1 (9, 5) 1 5 (8, 5) 0 (8, 5) 0 (8,5) 0 (8, 5) 0 6 (10, 2)  1 (10, 5)  0 (10, 2)  1 (10, 5)  0 7 (8, 2) 1(8, 2) 1 (8, 2) 1 (8, 2) 1 8 (6, 2) 1 (6, 5) 0 (6, 2) 1 (6, 5) 0 9 (8,5) 1 (8, 5) 1 10 (3, 5) 0 (3, 5) 0 11 (2, 5) 0 (2, 5) 0 12 (5, 2) 1 (5,5) 0 13 (4, 2) 1 (4, 5) 0 14 (3, 2) 1 (3, 2) 1 15 (2, 2) 1 (2, 2) 1 16(1, 2) 1 (1, 5) 0 17 (0, 2) 1 (0, 5) 0 18 (3, 5) 1 19 (2, 5) 1 20 (11,1)  1 (11, 1)  1 (11, 1)  1 21 (9, 1) 1 (9, 1) 1 (9, 1) 1 22 (7, 1) 1(7, 1) 1 (7, 1) 1 23 (10, 1)  1 (10, 1)  1 24 (8, 1) 1 (8, 1) 1 25(6, 1) 1 (6, 1) 1 26 (5, 1) 1 27 (4, 1) 1 28 (3, 1) 1 29 (2, 1) 1 30(1, 1) 1 31 (0, 1) 1 Note: n_(s)′ = n_(s) mod 2. Configurations 0-19 fornormal subframes are available for frame structure types 1, 2 and 3.Configurations 20-31 and configurations for special subframes areavailable for frame structure type 2 only.

TABLE 15 Mapping from CSI reference signal configuration to (k′, l′) forextended cyclic prefix. Number of CSI reference signals configured 1 or2 4 8 Normal Special Normal Special Normal Special CSI-RS subframesubframe subframe subframe Subframe subframe config. (k′, l′) n_(s)′(k′, l′) n_(s)′ (k′, l′) n_(s)′ (k′, l′) n_(s)′ (k′, l′) n_(s)′ (k′, l′)n_(s)′ 0 (11, 4)  0 (11, 4)  0 (11, 4)  0 (11, 4)  0 (11, 4) 0 (11, 4) 01 (9, 4) 0 (9, 4) 0 (9, 4) 0 (9, 4) 0  (9, 4) 0  (9, 4) 0 2 (10, 4)  1(10, 4)  1 (10, 4) 1 3 (9, 4) 1 (9, 4) 1  (9, 4) 1 4 (5, 4) 0 (5, 4) 0(5, 4) 0 (5, 4) 0 5 (3, 4) 0 (3, 4) 0 (3, 4) 0 (3, 4) 0 6 (4, 4) 1 (4,4) 1 7 (3, 4) 1 (3, 4) 1 8 (8, 4) 0 (8, 4) 0 9 (6, 4) 0 (6, 4) 0 10 (2,4) 0 (2, 4) 0 11 (0, 4) 0 (0, 4) 0 12 (7, 4) 1 13 (6, 4) 1 14 (1, 4) 115 (0, 4) 1 16 (11, 1)  1 (11, 1)  1 (11, 1)  1 (11, 1)  1 (11, 1) 1(11, 1) 1 17 (10, 1)  1 (10, 1)  1 (10, 1)  1 (10, 1)  1 (10, 1) 1(10, 1) 1 18 (9, 1) 1 (9, 1) 1 (9, 1) 1 (9, 1) 1  (9, 1) 1  (9, 1) 1 19(5, 1) 1 (5, 1) 1 (5, 1) 1 (5, 1) 1 20 (4, 1) 1 (4, 1) 1 (4, 1) 1 (4, 1)1 21 (3, 1) 1 (3, 1) 1 (3, 1) 1 (3, 1) 1 22 (8, 1) 1 (8, 1) 1 23 (7, 1)1 (7, 1) 1 24 (6, 1) 1 (6, 1) 1 25 (2, 1) 1 (2, 1) 1 26 (1, 1) 1 (1, 1)1 27 (0, 1) 1 (0, 1) 1 Note: n_(s)′ = n_(s) mod 2. Configurations 0-15for normal subframes are available for both frame structure type 1 andtype 2. Configurations 16-27 and configurations for special subframesare available for frame structure type 2 only.

TABLE 16 P_(C) in CSI-RS-Config UE assumption on reference PDSCHtransmitted power for CSI feedback P_(C), if the UE is configured intransmission mode 9. UE assumption on reference PDSCH transmitted powerfor CSI feedback P_(C) for each CSI process, if the UE is configured intransmission mode 10. If CSI subframe sets C_(CSI,0) and C_(CSI,1) areconfigured by higher layers for a CSI process, pc is configured for eachCSI subframe set of the CSI process.

In addition, in the disclosure, the UE transmits the feedback 3601 of ameasurement result for the CSI-RS to the target gNB. Table 17 belowshows the contents of feedback by the UE.

TABLE 17 Contents of CSI-RS feedback For each measurement, the followinginformation is sent to the target gNB. Resource index Based on thetime-frequency resources, the UE can identify the beam on which CSI-RSis received Subframe index Based on the subframe, the UE can identifythe beam on which CSI-RS is received Antenna port index Based on theantenna port, the UE can identify the beam on which CSI-RS is receivedCSI-RS beam index Based on the beam index (if it is included in CSI-RS),the UE can identify the beam on which CSI-RS is received RSRP (or RSRQ)RSRP (or RSRQ) measured by CSI-RS

[Handover: Proposed 2]

Referring to FIG. 37 , an embodiment of Handover: proposed 2 will bedescribed.

1. The serving gNB provides measurement configuration information to theUE at operation S3710.

2. The UE performs measurement, based on the measurement configurationinformation received from the serving gNB.

A. Here, the UE measures the signal strength or quality of the SStransmitted from the serving gNB and the target gNB.

3. If any event that the signal strength of the target gNB is greaterthan the signal strength of the serving gNB by offset is detected atoperation S3720 through a comparison of signal strength, the UEtransmits a measurement report to the serving gNB at operation S3740.

4. When the measurement report is received from the UE, the serving gNBtransmits a handover request to the target gNB at operation S3750 toperform an admission control.

5. The serving gNB transmits a handover command to the UE at operationS3760 to provide information necessary for the UE to access the targetgNB.

6. Based on information included in the handover command, the UEtransmits a RAP to the target gNB at operation S3770.

A. Here, the target gNB may receive the RAP of the UE while sweeping awide beam used to transmit the SS. In this case, the target gNBmemorizes a wide beam used to receive the RAP of the UE and uses it atthe next step. If the target gNB receives the RAP of the UE through aplurality of wide beams, the target gNB memorizes a wide beam having thehighest signal strength and uses it at the next step.

7. After receiving the RAP from the UE, the target gNB transmits a RARto the UE at operation S3780.

A. After receiving the RAP, the target gNB notifies a TX timing andpower adjusting level to the UE through the RAR and, if necessary,requests the UE to transmit the RAP again. After this uplinksynchronization, the target gNB allocates a UL grant so that the UE cantransmit a handover confirm.

B. Additionally, in the disclosure, the target gNB transmits CSI-RSconfiguration information 3700 together with the RAR to the UE. Thedetails of the CSI-RS configuration information are as described above.

8. The target gNB transmits at operation S3790 the CSI-RS through aplurality of narrow beams corresponding to the wide beam used forreceiving the RAP.

9. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the target gNB.

10. The UE with the uplink synchronization receives the RAR andtransmits the handover confirm to the target gNB through the UL grantincluded in the RAR at operation S3791.

A. Through this, the UE completes the handover from the serving gNB tothe target gNB.

11. The target gNB allocates a UL grant for feedback of a CSI-RSmeasurement result to the UE at operation S3792.

12. Using the allocated UL grant, the UE transmits the feedback of theCSI-RS measurement result to the target gNB at operation S3793.

13. Based on the CSI-RS feedback of the UE, the target gNB selects anarrow beam to be used by the UE and notifies it to the UE at operationS3794.

[Handover: Proposed 3]

Referring to FIG. 38 , an embodiment of Handover: proposed 3 will bedescribed.

1. The serving gNB provides measurement configuration information to theUE at operation S3810.

2. The UE performs measurement, based on the measurement configurationinformation received from the serving gNB.

A. Here, the UE measures the signal strength or quality of the SStransmitted from the serving gNB and the target gNB.

3. If any event that the signal strength of the target gNB is greaterthan the signal strength of the serving gNB by offset is detected atoperation S3820 through a comparison of signal strength, the UEtransmits a measurement report to the serving gNB at operation S3840.

4. When the measurement report is received from the UE, the serving gNBtransmits a handover request to the target gNB at operation S3850 toperform an admission control.

A. In the disclosure, the serving gNB delivers information contained inthe measurement report to the target gNB. This information includes anSS beam index of the target gNB measured by the UE and correspondingsignal strength.

B. Also, the target gNB determines CSI-RS configuration, based on themeasurement report received from the serving gNB, and then delivers itto the serving gNB through a handover request ACK.

5. The serving gNB transmits a handover command to the UE at operationS3860 to provide information necessary for the UE to access the targetgNB.

A. Additionally, in the disclosure, the serving gNB transmits CSI-RSconfiguration information 3800 together with the handover command to theUE. The details of the CSI-RS configuration information are as describedabove.

6. Based on information included in the handover command, the UEtransmits a RAP to the target gNB at operation S3870.

A. Here, the target gNB may receive the RAP of the UE while sweeping awide beam used to transmit the SS. In this case, the target gNBmemorizes a wide beam used to receive the RAP of the UE and uses it atthe next step. If the target gNB receives the RAP of the UE through aplurality of wide beams, the target gNB memorizes a wide beam having thehighest signal strength and uses it at the next step.

7. After receiving the RAP from the UE, the target gNB transmits a RARto the UE at operation S3880.

A. After receiving the RAP, the target gNB notifies a TX timing andpower adjusting level to the UE through the RAR and, if necessary,requests the UE to transmit the RAP again. After this uplinksynchronization, the target gNB allocates a UL grant so that the UE cantransmit a handover confirm.

B. Additionally, in the disclosure, the target gNB transmits CSI-RSconfiguration information 3600 together with the RAR to the UE. Thedetails of the CSI-RS configuration information will be described afterthe entire operation description.

8. The target gNB transmits at operation S3890 the CSI-RS through aplurality of narrow beams corresponding to the wide beam used forreceiving the RAP.

9. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the target gNB.

10. The UE with the uplink synchronization receives the RAR andtransmits the handover confirm to the target gNB through the UL grantincluded in the RAR at operation S3891.

A. When transmitting the handover confirm, the UE also transmitsfeedback 3801 of a measurement result for the CSI-RS. At this time, theUE utilizes the UL grant included in the RAR.

B. Through this, the UE completes the handover from the serving gNB tothe target gNB.

11. Based on the CSI-RS feedback of the UE, the target gNB selects anarrow beam to be used by the UE and notifies it to the UE at operationS3892.

[Handover: Proposed 4]

Referring to FIG. 39 , an embodiment of Handover: proposed 4 will bedescribed.

1. The serving gNB provides measurement configuration information to theUE at operation S3910.

2. The UE performs measurement, based on the measurement configurationinformation received from the serving gNB.

A. Here, the UE measures the signal strength or quality of the SStransmitted from the serving gNB and the target gNB.

3. If any event that the signal strength of the target gNB is greaterthan the signal strength of the serving gNB by offset is detected atoperation S3920 through a comparison of signal strength, the UEtransmits a measurement report to the serving gNB at operation S3940.

4. When the measurement report is received from the UE, the serving gNBtransmits a handover request to the target gNB at operation S3950 toperform an admission control.

A. In the disclosure, the serving gNB delivers information contained inthe measurement report to the target gNB. This information includes anSS beam index of the target gNB measured by the UE and correspondingsignal strength.

B. Also, the target gNB determines CSI-RS configuration, based on themeasurement report received from the serving gNB, and then delivers itto the serving gNB through a handover request ACK.

5. The serving gNB transmits a handover command to the UE at operationS3960 to provide information necessary for the UE to access the targetgNB.

A. Additionally, in the disclosure, the serving gNB transmits CSI-RSconfiguration information 3900 together with the handover command to theUE. The details of the CSI-RS configuration information are as describedabove.

6. The target gNB transmits at operation S3970 the CSI-RS through aplurality of narrow beams corresponding to a wide beam having thehighest signal strength measured by the UE and contained in themeasurement report.

7. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the target gNB.

8. Based on information included in the handover command, the UEtransmits a RAP to the target gNB at operation S3980.

9. After receiving the RAP from the UE, the target gNB transmits a RARto the UE at operation S3990.

A. After receiving the RAP, the target gNB notifies a TX timing andpower adjusting level to the UE through the RAR and, if necessary,requests the UE to transmit the RAP again. After this uplinksynchronization, the target gNB allocates a UL grant so that the UE cantransmit a handover confirm.

10. The UE with the uplink synchronization receives the RAR andtransmits the handover confirm to the target gNB through the UL grantincluded in the RAR at operation S3991.

A. When transmitting the handover confirm, the UE also transmitsfeedback 3901 of a measurement result for the CSI-RS. At this time, theUE utilizes the UL grant included in the RAR.

B. Through this, the UE completes the handover from the serving gNB tothe target gNB.

11. Based on the CSI-RS feedback of the UE, the target gNB selects anarrow beam to be used by the UE and notifies it to the UE at operationS3992.

[Handover: Proposed 5]

Referring to FIG. 40 , an embodiment of Handover: proposed 5 will bedescribed.

1. The serving gNB provides measurement configuration information to theUE at operation S4010.

2. The UE performs measurement, based on the measurement configurationinformation received from the serving gNB.

A. Here, the UE measures the signal strength or quality of the SStransmitted from the serving gNB and the target gNB.

3. If any event that the signal strength of the target gNB is greaterthan the signal strength of the serving gNB by offset is detected atoperation S4020 through a comparison of signal strength, the UEtransmits a measurement report to the serving gNB at operation S4040.

4. When the measurement report is received from the UE, the serving gNBtransmits a handover request to the target gNB at operation S4050 toperform an admission control.

A. In the disclosure, the serving gNB delivers information contained inthe measurement report to the target gNB. This information includes anSS beam index of the target gNB measured by the UE and correspondingsignal strength.

B. Also, the target gNB determines CSI-RS configuration, based on themeasurement report received from the serving gNB, and then delivers itto the serving gNB through a handover request ACK.

5. The serving gNB transmits a handover command to the UE at operationS4060 to provide information necessary for the UE to access the targetgNB.

A. Additionally, in the disclosure, the serving gNB transmits CSI-RSconfiguration information 4000 together with the handover command to theUE. The details of the CSI-RS configuration information are as describedabove.

6. Based on information included in the handover command, the UEtransmits a RAP to the target gNB at operation S4070.

A. Here, the target gNB may receive the RAP of the UE while sweeping awide beam used to transmit the SS. In this case, the target gNBmemorizes a wide beam used to receive the RAP of the UE and uses it atthe next step. If the target gNB receives the RAP of the UE through aplurality of wide beams, the target gNB memorizes a wide beam having thehighest signal strength and uses it at the next step.

7. After receiving the RAP from the UE, the target gNB transmits a RARto the UE at operation S4080.

A. After receiving the RAP, the target gNB notifies a TX timing andpower adjusting level to the UE through the RAR and, if necessary,requests the UE to transmit the RAP again. After this uplinksynchronization, the target gNB allocates a UL grant so that the UE cantransmit a handover confirm.

B. Additionally, in the disclosure, the RAR contains an indicator 4001for instructing the UE on CSI-RS measurement.

8. If the CSI-RS measurement instruction indicator contained in the RARis set to 1, the target gNB transmits at operation S4090 the CSI-RSthrough a plurality of narrow beams corresponding to a wide beam usedfor receiving the RAP.

A. If the CSI-RS measurement instruction indicator contained in the RARis set to 0, the target gNB does not transmit the CSI-RS.

9. In addition, if the CSI-RS measurement instruction indicatorcontained in the RAR is set to 1, the UE measures the signal strength orquality of the CSI-RS transmitted by the target gNB, based on the CSI-RSconfiguration information transmitted together with the handovercommand.

A. If the CSI-RS measurement instruction indicator contained in the RARis set to 0, the UE does not perform an operation related to the CSI-RSmeasurement since the target gNB does not transmit the CSI-RS.

10. The UE with the uplink synchronization receives the RAR andtransmits the handover confirm to the target gNB through the UL grantincluded in the RAR at operation S4091.

A. When transmitting the handover confirm, the UE also transmitsfeedback 4002 of a measurement result for the CSI-RS. At this time, theUE utilizes the UL grant included in the RAR.

B. Through this, the UE completes the handover from the serving gNB tothe target gNB.

11. Based on the CSI-RS feedback of the UE, the target gNB selects anarrow beam to be used by the UE and notifies it to the UE at operationS4092.

[Handover: Proposed 6]

Referring to FIG. 41 , an embodiment of Handover: proposed 6 will bedescribed.

1. The serving gNB provides measurement configuration information to theUE at operation S4110.

2. The UE performs measurement, based on the measurement configurationinformation received from the serving gNB.

A. Here, the UE measures the signal strength or quality of the SStransmitted from the serving gNB and the target gNB.

3. If any event that the signal strength of the target gNB is greaterthan the signal strength of the serving gNB by offset is detected atoperation S4120 through a comparison of signal strength, the UEtransmits a measurement report to the serving gNB at operation S4140.

4. When the measurement report is received from the UE, the serving gNBtransmits a handover request to the target gNB at operation S4150 toperform an admission control.

A. In the disclosure, the serving gNB delivers information contained inthe measurement report to the target gNB. This information includes anSS beam index of the target gNB measured by the UE and correspondingsignal strength.

B. Also, the target gNB determines CSI-RS configuration, based on themeasurement report received from the serving gNB, and then delivers itto the serving gNB through a handover request ACK.

5. The serving gNB transmits a handover command to the UE at operationS4160 to provide information necessary for the UE to access the targetgNB.

A. Additionally, in the disclosure, the serving gNB transmits CSI-RSconfiguration information 4100 together with the handover command to theUE. The details of the CSI-RS configuration information are as describedabove.

6. Based on information included in the handover command, the UEtransmits a RAP to the target gNB at operation S4170.

A. Here, the target gNB may receive the RAP of the UE while sweeping awide beam used to transmit the SS. In this case, the target gNBmemorizes a wide beam used to receive the RAP of the UE and uses it atthe next step. If the target gNB receives the RAP of the UE through aplurality of wide beams, the target gNB memorizes a wide beam having thehighest signal strength and uses it at the next step.

7. After receiving the RAP from the UE, the target gNB transmits a RARto the UE at operation S4180.

A. After receiving the RAP, the target gNB notifies a TX timing andpower adjusting level to the UE through the RAR and, if necessary,requests the UE to transmit the RAP again. After this uplinksynchronization, the target gNB allocates a UL grant so that the UE cantransmit a handover confirm.

B. Additionally, in the disclosure, using the RAR, the target gNB mayinstruct the UE to measure subset 4101 only of CSI-RS transmissionresources specified in the CSI-RS configuration.

C. Here, the target gNB may restrict the antenna port for transmissionof the CSI-RS in information included in the CSI-RS configurationthrough the RAR and notify this restriction to the UE. For example, evenif the previously transmitted CSI-RS configuration indicates fourantenna ports, the target gNB may inform, through the RAR, the UE thatthe CSI-RS will be transmitted using only two antenna ports.

D. In addition, even if the previously transmitted CSI-RS configurationindicates M SS beams or CSI-RS beam sets, the target gNB may inform,through the RAR, the UE that the CSI-RS will be transmitted for only N(<M) SS beams or CSI-RS beam sets.

E. In addition, even if the previously transmitted CSI-RS configurationindicates M resource blocks, the target gNB may inform, through the RAR,the UE that the CSI-RS will be transmitted using only N (<M) resourceblocks.

F. In addition, even if the previously transmitted CSI-RS configurationindicates M subframes as a period, the target gNB may inform, throughthe RAR, the UE that the CSI-RS will be transmitted actually at a periodof N (<M) subframes.

G. In the disclosure, the CSI-RS configuration information istransmitted together with the handover command. At this time, the targetgNB determines the CSI-RS configuration, based on the signal strength ofthe target gNB contained in the measurement report, and transmits it tothe UE. However, the UE transmits the uplink RAP to the target gNB afterreceiving the handover command, so that the target gNB can more exactlyidentify the CSI-RS beam set corresponding to the SS beam fortransmission of the CSI-RS. Therefore, in the disclosure, the target gNBmay use a part of CSI-RS transmission resources included in the CSI-RSconfiguration information so as to transmit the CSI-RS beam setcorresponding to the RAP receiving SS beam.

8. The target gNB transmits at operation S4190 the CSI-RS through aplurality of narrow beams corresponding to a wide beam used forreceiving the RAP.

A. Here, the CSI-RS may be transmitted using only a part of the CSI-RStransmission resources specified in the CSI-RS configuration, asinstructed to the UE in the RAR.

9. The UE measures the signal strength or quality of the CSI-RStransmitted by the target gNB, based on CSI-RS subset information 4101contained in the RAR as well as the CSI-RS configuration informationtransmitted together with the handover command.

10. The UE with the uplink synchronization receives the RAR andtransmits the handover confirm to the target gNB through the UL grantincluded in the RAR at operation S4191.

A. When transmitting the handover confirm, the UE also transmitsfeedback 4102 of a measurement result for the CSI-RS. At this time, theUE utilizes the UL grant included in the RAR.

B. Through this, the UE completes the handover from the serving gNB tothe target gNB.

11. Based on the CSI-RS feedback of the UE, the target gNB selects anarrow beam to be used by the UE and notifies it to the UE at operationS4192.

Next, the operation of the disclosure will be described in a situationwhere the idle mode UE initially accesses the gNB. An initial accessoperation is as follows.

[Initial Access]

FIG. 42 is a flow diagram illustrating a random access operationaccording to an embodiment of the disclosure.

Referring to FIG. 42 , the initial access operation will be described.

1. While performing reception (RX) beam sweeping, the UE measures thesignal strength or quality of each beam for the SS transmitted by thegNB through TX beam sweeping.

2. When the SS is measured, the UE transmits an RAP toward one or moregNB beams having the greatest signal strength at operation S4210.

3. When the RAP is received, the gNB transmits an RAR to the UE by usingone or more gNB beams having the greatest signal strength at operationS4220.

A. The RAR contains a UL grant so that the UE can transmit an RRCconnection request.

4. After receiving the RAR, the UE transmits the RRC connection requestto the gNB through the UL grant contained in the RAR at operation S4230.

5. After receiving the RRC connection request from the UE, the gNBtransmits an RRC connection setup to the UE at operation S4240.

6. After receiving the RRC connection setup from the gNB, the UEtransmits an RRC connection setup complete to the gNB at operationS4250.

A. Through this, the UE completes the initial access to the gNB.

Since the above operation is the same as the initial access operationdefined in LTE, detailed description of each message is omitted. Thisinitial access operation is designed for a situation where the gNB usesonly one RS. This is not suitable for a situation considered in thedisclosure, i.e., a situation where the determination of whether toperform the initial access is based on the SS transmitted on a widebeam, but the actual data transmission/reception uses a narrow beam.Unsuitableness is because the UE fails to determine a narrow beam to beused for transmitting and receiving data to and from the gNB despite thecompletion of the initial access.

In the disclosure, the UE determines whether to perform the initialaccess, through the measurement of the SS transmitted on a wide beam,and then performs the measurement of the CSI-RS transmitted on a narrowbeam during the initial access procedure so as to find as soon aspossible the narrow beam to be used with the gNB. Hereinafter, variousembodiments will be described.

FIGS. 43 to 47 are flow diagrams illustrating various methods fordetermining a beam to be used for data transmission and reception in arandom access process according to various embodiments of thedisclosure.

[Initial Access: Proposed 1]

Referring to FIG. 43 , an embodiment of Initial access: proposed 1 willbe described.

1. While performing RX beam sweeping, the UE measures the signalstrength or quality of each beam for the SS transmitted through TX beamsweeping by the gNB.

2. When the SS is measured, the UE transmits an RAP toward one or moregNB beams having the greatest signal strength at operation S4310.

3. When the RAP is received, the gNB transmits an RAR to the UE by usingone or more gNB beams having the greatest signal strength at operationS4320.

A. The RAR contains a UL grant so that the UE can transmit an RRCconnection request.

B. Additionally, in the disclosure, CSI-RS configuration information4300 is transmitted together with the RAR to the UE. The details of theCSI-RS configuration information are as described above.

4. The gNB transmits at operation S4330 the CSI-RS through a pluralityof narrow beams corresponding to a wide beam used for receiving the RAPor corresponding to a beam having the greatest signal strength amongwide beams used for receiving the RAP.

5. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the gNB.

6. After receiving the RAR, the UE transmits the RRC connection requestto the gNB through the UL grant contained in the RAR at operation S4340.

A. When transmitting the RRC connection request, the UE furthertransmits feedback 4301 of a CSI-RS measurement result.

7. After receiving the RRC connection request from the UE, the gNBtransmits an RRC connection setup to the UE at operation S4350.

A. Here, the RRC connection setup may be transmitted using a beam havingthe greatest signal strength from among a narrow beam included in theCSI-RS feedback and a wide beam used for transmitting the RAR.

8. After receiving the RRC connection setup from the gNB, the UEtransmits an RRC connection setup complete to the gNB at operationS4360.

A. Through this, the UE completes the initial access to the gNB.

[Initial Access: Proposed 2]

Referring to FIG. 44 , an embodiment of Initial access: proposed 2 willbe described.

1. While performing RX beam sweeping, the UE measures the signalstrength or quality of each beam for the SS transmitted through TX beamsweeping by the gNB.

2. When the SS is measured, the UE transmits an RAP toward one or moregNB beams having the greatest signal strength at operation S4410.

3. When the RAP is received, the gNB transmits an RAR to the UE by usingone or more gNB beams having the greatest signal strength at operationS4420.

A. The RAR contains a UL grant so that the UE can transmit an RRCconnection request.

B. Additionally, in the disclosure, CSI-RS configuration information4400 is transmitted together with the RAR to the UE. The details of theCSI-RS configuration information are as described above.

4. The gNB transmits at operation S4430 the CSI-RS through a pluralityof narrow beams corresponding to a wide beam used for receiving the RAPor corresponding to a beam having the greatest signal strength amongwide beams used for receiving the RAP.

5. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the gNB.

6. After receiving the RAR, the UE transmits the RRC connection requestto the gNB through the UL grant contained in the RAR at operation S4440.

7. After receiving the RRC connection request from the UE, the gNBtransmits an RRC connection setup to the UE at operation S4450.

8. After receiving the RRC connection setup from the gNB, the UEtransmits an RRC connection setup complete to the gNB at operationS4460.

A. When transmitting the RRC connection setup complete, the UE furthertransmits feedback 4401 of a CSI-RS measurement result.

B. Through this, the UE completes the initial access to the gNB.

[Initial Access: Proposed 3]

Referring to FIG. 45 , an embodiment of Initial access: proposed 3 willbe described.

1. While performing RX beam sweeping, the UE measures the signalstrength or quality of each beam for the SS transmitted through TX beamsweeping by the gNB.

2. When the SS is measured, the UE transmits an RAP toward one or moregNB beams having the greatest signal strength at operation S4510.

3. When the RAP is received, the gNB transmits an RAR to the UE by usingone or more gNB beams having the greatest signal strength at operationS4520.

A. The RAR contains a UL grant so that the UE can transmit an RRCconnection request.

B. Additionally, in the disclosure, CSI-RS configuration information4500 is transmitted together with the RAR to the UE. The details of theCSI-RS configuration information are as described above.

4. The gNB transmits at operation S4530 the CSI-RS through a pluralityof narrow beams corresponding to a wide beam used for receiving the RAPor corresponding to a beam having the greatest signal strength amongwide beams used for receiving the RAP.

5. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the gNB.

6. After receiving the RAR, the UE transmits the RRC connection requestto the gNB through the UL grant contained in the RAR at operation S4540.

7. After receiving the RRC connection request from the UE, the gNBtransmits an RRC connection setup to the UE at operation S4550.

8. After receiving the RRC connection setup from the gNB, the UEtransmits an RRC connection setup complete to the gNB at operationS4560.

A. Through this, the UE completes the initial access to the gNB.

9. The gNB allocates a UL grant for receiving a CSI-RS feedback to theUE, and the UE transmits feedback of a CSI-RS measurement result to thegNB through the allocated UL grant at operation S4570.

[Initial Access: Proposed 4]

Referring to FIG. 46 , an embodiment of Initial access: proposed 4 willbe described.

1. While performing RX beam sweeping, the UE measures the signalstrength or quality of each beam for the SS transmitted through TX beamsweeping by the gNB.

2. When the SS is measured, the UE transmits an RAP toward one or moregNB beams having the greatest signal strength at operation S4610.

3. When the RAP is received, the gNB transmits an RAR to the UE by usingone or more gNB beams having the greatest signal strength at operationS4620.

A. The RAR contains a UL grant so that the UE can transmit an RRCconnection request.

4. After receiving the RAR, the UE transmits the RRC connection requestto the gNB through the UL grant contained in the RAR at operation S4630.

5. After receiving the RRC connection request from the UE, the gNBtransmits an RRC connection setup to the UE at operation S4640.

A. Additionally, in the disclosure, CSI-RS configuration information4600 is transmitted together with the RAR to the UE. The details of theCSI-RS configuration information are as described above.

6. The gNB transmits at operation S4650 the CSI-RS through a pluralityof narrow beams corresponding to a wide beam used for receiving the RAPor corresponding to a beam having the greatest signal strength amongwide beams used for receiving the RAP.

7. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the gNB.

8. After receiving the RRC connection setup from the gNB, the UEtransmits an RRC connection setup complete to the gNB at operationS4660.

A. When transmitting the RRC connection setup complete, the UE furthertransmits feedback 4601 of a CSI-RS measurement result.

B. Through this, the UE completes the initial access to the gNB.

[Initial Access: Proposed 5]

Referring to FIG. 47 , an embodiment of Initial access: proposed 5 willbe described.

1. While performing RX beam sweeping, the UE measures the signalstrength or quality of each beam for the SS transmitted through TX beamsweeping by the gNB.

2. When the SS is measured, the UE transmits an RAP toward one or moregNB beams having the greatest signal strength at operation S4710.

3. When the RAP is received, the gNB transmits an RAR to the UE by usingone or more gNB beams having the greatest signal strength at operationS4720.

A. The RAR contains a UL grant so that the UE can transmit an RRCconnection request.

4. After receiving the RAR, the UE transmits the RRC connection requestto the gNB through the UL grant contained in the RAR at operation S4730.

5. After receiving the RRC connection request from the UE, the gNBtransmits an RRC connection setup to the UE at operation S4740.

A. Additionally, in the disclosure, CSI-RS configuration information4700 is transmitted together with the RAR to the UE. The details of theCSI-RS configuration information are as described above.

6. The gNB transmits at operation S4750 the CSI-RS through a pluralityof narrow beams corresponding to a wide beam used for receiving the RAPor corresponding to a beam having the greatest signal strength amongwide beams used for receiving the RAP.

7. Based on the CSI-RS configuration information, the UE measures thesignal strength or quality of the CSI-RS transmitted by the gNB.

8. After receiving the RRC connection setup from the gNB, the UEtransmits an RRC connection setup complete to the gNB at operationS4760.

A. Through this, the UE completes the initial access to the gNB.

9. The gNB allocates a UL grant for receiving a CSI-RS feedback to theUE, and the UE transmits feedback 4701 of a CSI-RS measurement result tothe gNB through the allocated UL grant at operation S4770.

Fourth Embodiment

In the LTE system, a multi-carrier scheme such as carrier aggregation(CA) and dual connectivity (DC) for handling a plurality of componentcarriers (CC) together has been introduced in order to support a wideband. Aggregation of up to 32 CCs can support a bandwidth of 640 MHz incase of 20 MHz CC. However, if a scheme such as LTE CA is applied tosupport ultra-wideband (e.g., 1 GHz) in a 5G new radio (NR) system, thenumber of combinations of CCs to be used by the terminal increasesexponentially, and the size of a capability report performed by theterminal also increases. Therefore, the terminal has no choice but tooperate only within a limited CC combination. In addition, as the numberof CCs increases in the CA, the reception complexity of the terminal andthe control complexity of the base station are also increased. However,in spite of such problems of the CA or DC, the CA or DC has greaterflexibility in the use of resources than a single carrier. This isbecause the secondary (SCell) addition/release allows a change of anexpanded band and also the cross-carrier scheduling allows scheduling ofresource transmission/reception for other CCs.

In addition, the 5G system defines an energy-efficient operation withthe primary goal of improving the power efficiency [bit/J] of theterminal and base station network by more than 1000 times. For thispurpose, it is necessary to control the size of an operating band of theterminal in order to solve a possibility of additional power consumptioncaused by wideband transmission which is essential in the operation of asuper-high frequency band (mmW).

The disclosure proposes operating schemes of a terminal and a basestation for achieving energy efficiency key performance indicators (KPI)being discussed in 3GPP RAN 5G system information (SI). Specifically,the disclosure relates to the layer 1/2 operation of a terminal and abase station in a mobile communication system. More specifically, thedisclosure relates to a method and apparatus for changing an operatingband of a terminal to reduce power consumption of the terminal when thebase station desires ultra-wideband signal transmission/reception withthe terminal.

The disclosure proposes a control and setup method for ultra widebandtransmission/reception in the 5G mobile communication system. Inparticular, a method for scheduling, handover, and power saving in theultra wideband is considered. In the 5G mobile communication system, itis expected that various services (or slices) such as enhanced mobilebroadband (eMBB), ultra reliable and low latency communication (URLLC),and enhanced machine type communication (eMTC) are to be supported. Thismay be understood in the same context that the voice over Internetprotocol (VoIP) and best effort (BE) services are supported in LTE whichis the fourth generation (4G) mobile communication system. In addition,it is expected that various numerologies are to be supported in the 5Gmobile communication system. This is specifically due to a difference insubcarrier spacing or transmission time interval (TTI). Therefore, TTIsof various lengths are expected to be supported in the 5G mobilecommunication system. This is one of distinctive features of the 5Gmobile communication system, compared to LTE in which only one kind ofTTI (1 ms) is supported. If the 5G mobile communication system supportsa TTI (e.g., 0.1 ms) which is much shorter than the 1 ms TTI of LTE, itis expected to be a great help to support URLLC which requires a shortdelay time. In the disclosure, the numerology is used as a term havingthe same meaning as subcarrier spacing, subframe length, symbol/sequencelength, and the like. Also, the terminals may be configured withdifferent bandwidths (BWs) in different numerology areas. The basestation may be also referred to as various terms such as gNB, eNB, NB,and BS. The terminal may be also referred to as various terms such asUE, MS, and STA.

FIG. 48 is a diagram illustrating an LTE scalable BW system according toan embodiment of the disclosure.

FIG. 49 is a diagram illustrating features of a 5G NR flexible BW systemaccording to an embodiment of the disclosure.

Referring to FIG. 48 , in order to support various BWs, LTE hasintroduced the concept of a scalable BW. According to FIG. 48 , the LTEsystem supports terminals having various BWs (e.g., 5/10/20 MHz) withthe same center frequency. For example, if the first UE 4810 supports 5MHz and the second UE 4820 supports 10 MHz, the LTE base stationappropriately configures a control channel and transmits a controlsignal so that both UEs can receive the control signal. However, thismethod extremely restricts resources that can be used by a terminalhaving a relatively small band when the total available bandwidth of thebase station is very large, namely, in the ultra wideband. For example,when the third UE 4830 operates at the edge of the base stationavailable band, this UE 4830 may not distinctively receive the controlsignal of the base station.

Referring to FIG. 49 , in the 5G NR communication system, the operatingband should be able to be flexibly configured. That is, after the RRCconnection setup is successful through an access BW 4900 configured fromthe synchronization signal reception and SI acquisition, the terminalmay switch the operating band (or operating BW) from a relatively narrowband (or narrow BW) 4910 to a relatively wide band (or wide BW) 4920under the control of the base station. Using the wide band, the terminalmay receive the control signal of the base station to contribute to theimprovement of the control signal performance or may perform datatransmission/reception (DL or UL) to improve the efficiency ofresources.

Also, in the 5G NR communication system, the terminal should be able totransmit and receive important control signals in order to maintain theconnection with the base station even in a certain band which is notsupported by the existing scalable BW system. In case of LTE, suchimportant control signals are transmitted via PCell by means of asignaling radio bearer (SRB). Also, in PCell, control signals forscheduling and hybrid automatic-repeat-request (HARQ) procedures inPCell itself and SCell are transmitted and received. In LTE, each ofPCell or SCell may be one independent cell. For each cell, a separateMAC entity and corresponding link adaptation and HARQ entity arerequired. However, in the 5G NR single carrier communication system, theentire band corresponds to one cell. Also, functions of PCell forterminal access, connection setup/maintenance, and datatransmission/reception should be basically provided.

Meanwhile, even if the base station operates in the ultra wideband, theterminal can perform transmission/reception only in a part of the entireband because of limited implementation and complexity. In order for theterminal to operate in a band larger than the maximum usable bandwidth(i.e., capable BW), it is necessary to operate in a time divisionmanner. For an easier management, the base station may divide the ultrawideband into bands or sub-bands having suitable sizes and instruct theterminal to perform, in a specific band, various functions (e.g.,control signal transmission/reception, data signaltransmission/reception, RS, measurement, scheduling, link adaptation,modulation coding scheme (MCS), HARQ, etc.). Also, the terminal mayjudge and receive the structure of a control channel and a referencesignal, based on the band.

FIG. 50 is a diagram illustrating various band division schemes in a 5GNR flexible BW system according to an embodiment of the disclosure.

Referring to FIG. 50 , in Case A, the UE1 5000 may operate only in apart, not in the entire, of the available band due to the fixed bandconfiguration.

In Case B, the UE2 5010 may not be supported in Band 4 because themaximum available bandwidth is smaller than the bandwidth 5011 of Band 4configured by the base station.

If the unit of bands is minimized as shown in Case C, it is possible tosupport UEs 5020 having various bandwidths because the band to be usedby the UE is represented by a bundle of small bands. However, too manybands may cause an increase of overload.

Therefore, as in Case D, a scheme of freely configuring the size ofbands is useful.

In order to solve the above problems when the base station divides theentire band into bands for the terminal, the disclosure considers ascheme in which the base station configures bands of different sizes forrespective terminals and the system can represent the band as acombination of sub-bands having the same size. Also, rather thanperforming independent scheduling, link adaptation, MCS, and HARQprocedures in a sub-band divided in view of the system, one scheduling,link adaptation, MCS, and HARQ procedure will be performed in a bandconfigured in view of the terminal.

The structure of a physical layer control channel should be designed tobe scalable to one or a plurality of sub-bands in one band. This meansthat it is possible to support a terminal having a band that can berepresented by at least a multiple of sub-bands in the band. The size ofa band which is a bundle of sub-bands is determined by at least one of achannel feature between a terminal and a base station, numerology, acontrol sub-band size, and a minimum packet size. The terminal performsone MAC function set (scheduling, MCS, HARQ, etc.) for one service.

The functions that can be provided by the system structure proposed bythe disclosure can be considered as follows.

-   -   Configuration of control/RS/CSI report/HARQ feedback per band    -   Self-/cross-band scheduling    -   Band-aggregation to transmit single transport block    -   Cross-band HARQ retransmission    -   RRM measurement    -   Power saving with adaptive BW

[Configuration of Control/RS/CSI Report/HARQ Feedback Per Band]

The base station can notify the range (i.e., start, size or centerfrequency, and bandwidth) of a band to the terminal by representing amultiple of a basic unit (RB or sub-band) when configuring the band.Since the position and range of a band are part of one carrier in whichthe network system operates, the base station can configure the band tothe terminal by means of the frequency offset and bandwidth for thecenter frequency of the entire carrier band. Alternatively, the basestation can configure the band to the terminal by means of the frequencyoffset and bandwidth for the center frequency at which a synchronizationsignal detected by the terminal is located. Meanwhile, the centerfrequency of a carrier band understood by the terminal may be always thecenter frequency of the synchronization signal detected by the terminal,be the same as the center frequency information of a carrier indicatedby the SI connected to the synchronization signal detected by theterminal, or be the same as the center frequency information of acarrier instructed by the base station in the RRC connection setupprocedure. The terminal understands the band range as a system band.Therefore, even if bands of different ranges are assigned, the terminalshould be designed to receive a signal in accordance with the samereception rule.

For example, the position of a reference signal (RS) or a controlchannel transmitted by the base station should be determined on thebasis of the start and size of a band configured for the terminal. Also,the position of a CSI report or HARQ feedback transmitted by theterminal should be determined on the basis of the start and size of aband configured for the terminal. Meanwhile, when a plurality of bandsare configured, the base station may further configure for the terminalwhether the HARQ process is to be shared for a plurality of bands orseparated for each band.

A band configured for the terminal to monitor is referred to as aprimary band (p-band). The terminal may not perform monitoring in aresource area other than the p-band unless there is any separatecontrol/configuration from the p-band.

A secondary band (s-band) may be selectively operated according to theconfiguration through the p-band, and the p-band and the s-band may bereferred to as a first radio frequency (RF) band and a second RF band,respectively. Also, the p-band may be activated to the active state fromamong at least one or more configured band candidates through the RRCmessage or MAC CE or DCI. Also, the s-band may be activated to theactive state from among at least one or more configured band candidatethrough the RRC message or MAC CE or DCI. Similarly, the base stationmay deactivate one or more bands from the active state to the inactivestate by transmitting a deactivation signal or message the terminalthrough the RRC message or MAC CE or DCI. In the disclosure, the activeband and the p-band are used as similar meaning, but the p-band requiresa combination of a DL band and a UL band at the time of configuration.Therefore, the p-band is the active band, but all active bands are notalways the p-band. Also, the p-band is not deactivated except for aseparate band switching procedure. In case of time division duplex(TDD), the frequency positions of the DL band and the UL band in thep-band may be the same.

The p-band configuration includes at least one DL band and one or moreUL bands, and the base station can instruct the terminal to configurethe p-band. When the terminal reports a UE capability report includingRF information to the base station, the base station can configure thep-band for each different RF of the terminal.

-   -   Hereinafter, the operation associated with band        switch/activation indication in single or multiple active bands        will be described.

The terminal may monitor one or more of configured bands at the sametime according to RF conditions. Therefore, it is advantageous in termsof scalability that a band indication of the base station is commonlyapplied to the terminals under different RF conditions. However, thebase station needs to know in advance other RF conditions of theterminal through a capability report of the terminal Otherwise, when anactivation instruction from Band #1 to Band #2 is issued for a certainterminal, there is a possibility of wrong operation because it isimpossible to know whether Band #1 is deactivated due to RF restrictionof the terminal.

When the terminal that operates in a single active band receives a bandactivation indication from the base station, the terminal switches tothe indicated band and deactivates the previous band. When the terminalthat operates in multiple active bands receives a band activationindication from the base station, the terminal activates the indicatedband and maintains the band in use.

However, the band configuration by the capability report of the terminalhas a possibility of wrong operation. Therefore, the base station shouldbe able to configure the maximum number of active bands of the terminaland to clearly indicate the deactivation of the band.

An activation/deactivation operation rule for the band may be configuredin advance according to one of the following two methods, or may beconfigured by the base station/network. In addition, this operation maybe equally applied to a case where a band switch/activation occurs inconjunction with a cross-band scheduling indication in addition to aseparate band activation indication of the base station.

a) Although multiple active bands are configured, each active band canonly switch to other deactivated band. Therefore, changing the number ofactive bands is possible only with RRC.

b) Multiple active band are configured, and activated/deactivatedindication is made for each band. Since the number of active bands canbe changed, the base station should be operated so that the maximumnumber of active bands of the terminal is not exceeded and all bands aredeactivated. If the base station instructs to exceed the maximum activeband, the terminal may operate, in the previous active bands, 1) todeactivate the initially activated band, 2) to deactivate the lastlyactivated band, 3) to deactivate the lowest band in the order of bandindex, 4) to deactivate the lowest band according to the priority ofbands configured by the base station, or 5) to deactivate a certain bandarbitrarily determined by the terminal. Also, the deactivated band maybe configured to exclude the p-band.

-   -   Hereinafter, a procedure for determining a moving point        including retuning latency when activating a band through DCI or        MAC CE will be described.

The RF retuning time may be varied according to a relation betweenswitching bands and an active band switching condition of the terminal.The base station may configure a time required for switching one band(e.g., the p-band) to other band to the terminal through the RRC, basedon the capability report of the terminal. If the terminal fails tocomply with this configuration, the terminal may reject the bandswitching for each band.

In case where the base station instructs the band switching through theDCI, 1) the terminal may consider a switching delay time from the DCIreception time (subframe/slot/mini-slot), already configured through theRRC, to the completion of switching. Therefore, the terminal may monitora control channel from the fastest valid control channel in the bandactivated after the switching delay time from the DCI reception time,based on a band identification (ID) included in the DCI. Alternatively,2) the switching delay time k from the DCI reception time(subframe/slot/mini-slot) to the completion of the switching may beincluded, together with the band ID, in the DCI. Accordingly, theterminal may monitor a control channel from the fastest valid controlchannel after a time determined according to the value of k.

In case where the base station instructs the band switching through theMAC CE, 1) the terminal may monitor a control channel from the fastestvalid control channel in the band activated after the switching delaytime from the HARQ ACK success time (subframe/slot/mini-slot) for theMAC CE reception to the completion of switching, by considering theswitching time already configured through the RRC, based on the band IDincluded in the MAC CE. Alternatively, 2) the terminal may consider theswitching delay time already configured through the RRC. The terminalmay monitor a control channel from the fastest valid control channel inthe band activated after the switching delay time from the time(subframe/slot/mini-slot), when the MAC determines the band switchingand transmits an indication to the PHY, to the completion of switching,based on the band ID included in the MAC CE. Alternatively, 3) theswitching delay time k from the MAC CE reception success time(subframe/slot/mini-slot) to the completion of the switching may beincluded, together with the band ID, in the MAC CE. Accordingly, theterminal may monitor a control channel from the fastest valid controlchannel in the band activated after the switching delay time from theMAC CE reception success time (subframe/slot/mini-slot) to completion ofswitching. Alternatively, 4) the switching delay time k from thetransmission time (subframe/slot/mini-slot) of HARQ ACK for the MAC CEreception success to the completion of the switching may be included,together with the band ID, in the MAC CE. Therefore, the terminal maymonitor a control channel from the fastest valid control channel in theband activated after the switching delay time from the transmission time(subframe/slot/mini-slot) of HARQ ACK for the MAC CE reception successto the completion of the switching. The terminal follows at least one ofthe operations described above.

[Self-/Cross-Band Scheduling]

FIG. 51 is a diagram illustrating a self/cross-band scheduling operationaccording to an embodiment of the disclosure.

Referring to FIG. 51 , through control sub-bands 5110, 5130, and 5150 ina p-band, the base station may schedule a data channel 5120 in the samesub-band, a data channel 5140 in other sub-band, or a control channel5160 in other sub-band.

The base station may control transmission/reception of signals through acontrol channel or a data channel of the terminal through a controlsub-band within a p-band configured for each terminal. The base stationmay indicate a downlink (DL) or uplink (UL) data transmission/receptionarea by means of self-band data scheduling or cross-band datascheduling. Also, the base station may instruct a change in the positionor size of a control sub-band in the same band by self-band controlscheduling. Also, the base station may indicate the position or size ofan additional control sub-band in other band by cross-band controlscheduling.

If the position or size of the second control sub-band is indicatedthrough the first control sub-band, the terminal checks whether thefirst control sub-band and the second control sub-band aresimultaneously monitored. If so, the terminal can simultaneously receivesignals through two control sub-bands. Otherwise, this means that theterminal monitors only the first control sub-band. Therefore, in orderto monitor the second control sub-band, a delay for a certain amount ofRF retuning is required.

In general, in case of UL scheduling, the base station can instruct theterminal on a predetermined delay value (e.g., 4 ms) or a separate delayvalue through a control sub-band.

In the system considered in the disclosure, cross-band scheduling inwhich a bandwidth change may be required, even in case of DL scheduling,needs to separately indicate a specific subframe that follows in timewhile physical downlink shared channel (PDSCH) for datatransmission/reception is normally indicated in the same subframe asPDCCH.

This is because a processing time for retuning of the RF and baseband(BB) circuit is required as the position of the used band abruptlychanges. That is, in consideration of the available band informationincluded in the capability report of the terminal and the degree ofchange of the used band of the terminal by the control of the basestation, the base station should instruct the terminal to transmit andreceive a DL signal after a delay time configured after the transmissionof a control signal. This delay time may be included in each controlsignal, or the base station may previously configure at least one delaytime value during a capability negotiation and connection setupprocedure of the terminal. Since the delay is greater in case where theused band of the terminal completely changes than in case where the usedband of the terminal is partially overlapped and the bandwidth alone ischanged, the base station transmits the delay time through each controlsignal or transmit an index for two or more delay values through acontrol signal so that the terminal can perform a DL reception operationafter a suitable delay.

Meanwhile, the base station may perform asymmetric p-band configurationthat the terminal has different bands (position, size) in DL and UL.However, since main control functions are smoothly operated in thep-band when both DL and UL are supported, the terminal understands thep-band as one even if different bands are allocated.

[Adaptive BW Method and Procedure for Power Saving]

The LTE system provides a power saving mode (PSM) and a discontinuousreception (DRX) so as to reduce power consumption. The PSM refers to astate in which only a tracking area update (TAU) or a routing areaupdate (RAU) is performed and paging is not received from the basestation. This is almost similar to power off, but the terminal needs notto re-attach to the network or re-establish the packet data network(PDN) connection because of being still registered in the network.

The DRX is classified into the idle mode DRX and the connected mode DRX.According to the idle mode DRX (i.e., idle-DRX), the idle mode UE doesnot receive a signal of the base station except for a period of time(paging frame number and paging occasion) for periodically monitoring apaging signal. In this case, since the terminal does not have the RRCconnection with the network, the network does not have contextinformation of the terminal. The terminal is regarded as beingregistered in the mobility management entity (MME) and residing within atracking area list (TAL). The purpose of the connected mode DRX is toreduce power consumption caused when the connected mode terminalmonitors a control signal of the base station (PDCCH) every DL subframe.If the terminal arbitrarily skips the monitoring of the DL subframe, itis difficult for the base station to control the terminal as desired.Therefore, the base station and the terminal should perform transmissionby the base station and reception by the terminal in the DL subframe ofa predetermined location.

The LTE connected DRX operation is as follows. The base station mayconfigure DRX-related parameters among RRC parameters through an RRCconnection setup request message or an RRC connection reestablishmentrequest message. The DRX-related parameters include, for example, a DRXcycle, an on-duration timer, and an inactivity timer. The DRX cycleindicates the length of a single duration in which the terminal repeatsON and OFF, and the on-duration timer indicates the length of theon-duration. The length of off-duration may be calculated from the DRXcycle and the on-duration timer. These parameters are expressed insubframe units. The terminal monitors a DL signal on PDCCH of the basestation during the on-duration indicated by the on-duration timer anddoes not monitor a DL signal on PDCCH of the base station in theoff-duration. If the terminal succeeds in receiving a DL signal in acertain subframe, the inactivity timer starts from that subframe. Theterminal should monitor a DL signal on PDCCH of the base station untilthe inactivity timer expires. After the last successful reception of aDL signal, the terminal does not monitor a DL signal if a subframecorresponding to the expiration time of the inactivity timer is reachedand this subframe belongs to the off-duration.

Specifically, the C-DRX may be classified into short DRX and long DRX,depending on the DRX cycle. In accordance with the activity of a DLsignal, the terminal always switches to the short DRX in each subframe,then switches to the long DRX, and switches again to a state of no DRXoperation when the long DRX cycle ends. To configure this operation, ashort DRX cycle timer is used to indicate the number of repetitions ofthe short DRX cycle. In case of the long DRX, the terminal switches to asleep state after one long DRX cycle. The base station may instruct thestart of the short or long DRX through a MAC command element (CE) sothat the terminal switches back to the short DRX or maintains the longDRX state. Exceptionally, at the DL HARQ packet retransmission definedas HARQ round trip time (RTT), the terminal should monitor a DL signalirrespective of the DRX. Also, if the UL HARQ packet retransmission isexpected, the terminal should monitor a DL control signal, i.e., a ULgrant, for a duration configured as a DRX retransmission timer.

According to LTE, the short DRX is represented as follows:[(SFN*10)+subframenumber]modulo(shortDRX-Cycle)=(drxStartOffset)modulo(shortDRX-Cycle)

According to LTE, the long DRX is represented as follows:[(SFN*10)+subframe number]modulo(longDRX-Cycle)=drxStartOffset

Similar equations may be used when applying the LTE connected mode DRX(C-DRX) to 5G NR.

If the LTE C-DRX is applied to 5G NR, the terminal that receiveshigh-speed data traffic will monitor a wideband DL signal of the basestation in the on-duration and will not monitor a DL signal in theoff-duration. However, depending on the characteristics of traffic, itis not necessary to receive a wideband DL signal every subframe. Forexample, in case of a streaming service, an encoding scheme fortransmitting only image variation information in periodic large-capacityinformation is used. Therefore, in the 5G NR communication system, thesize of bandwidth (BW) of a resource monitored by the terminal should beadaptively varied.

FIGS. 52 to 54 are diagrams illustrating examples of BW expansion andreduction operation by a physical layer control signal according tovarious embodiments of the disclosure.

If this variable BW control is performed on the L1 layer, i.e., thephysical layer, operations as shown in FIGS. 52 to 55 are possible. Inorder to save power, it is reasonable that the terminal is basically ina narrow BW state and, if necessary, switches to a wide BW.

Referring to FIG. 52 , therefore, the terminal monitors a narrowbandcontrol sub-band (CSB #1) 5210 provided by the L1 in the RRC connectionsetup step and, if an L1 signal 5230 instructing a BW expansion isreceived from the base station, monitors a wideband control sub-band(CSB #2) 5220 in a specific subframe.

An interval between the time point when the BW expansion instructioncontrol signal is received and the subframe where switching to CSB #2 isperformed is determined according to at least one of a) a fixedinterval, b) an interval configured by the RRC parameter, c) an intervalconfigured by the L1 control signal, d) an interval computable accordingto the BW capability information reported by the terminal and thecurrent terminal state, and e) whether the center frequency of the BW tobe switched is overlapped.

On the other hand, when the terminal continuously requests a largeamount of traffic, the BW expansion instruction control signal should befrequently transmitted, and in the worst case, half of a subframe can beserved in a narrow band due to restriction of a switching delay. Inaddition, frequent BW and RF switching may cause a terminal load andadditional power consumption.

Referring to FIG. 53 , an example is illustrated of further using a BWreduction instruction control signal to solve a problem when using onlya BW expansion instruction control signal.

According to this operation, the terminal monitors CBS #1 5310, switchesthe bandwidth to monitor CSB #2 5320 when the BW expansion instructioncontrol signal 5330 is received, and maintains the mode. Then, when theBW reduction instruction control signal 5360 is received through CSB #25340, the terminal switches the bandwidth to monitor CSB #1 5350.However, this method may cause an error in the operation of the terminalif the BW expansion or reduction instruction control signal fails to bereceived.

For example, although the base station sends the BW expansioninstruction control signal 5330 and sends a control signal (DCI) fordata transmission/reception through CSB #2 5320 of the instructedsubframe, the terminal may not receive the BW expansion instructioncontrol signal 5330. Because of being monitoring CSB #1, the terminaldoes not receive the DCI transmitted through CSB #2 5320. In this case,the base station does not know whether the terminal fails to receive theDCI transmitted through CSB #2 5320 even though the terminalsuccessfully receives the BW expansion indication control signal 5330,or the terminal fails to receive the BW expansion indication controlsignal 5330.

Also, if the terminal fails to receive a DL signal for a certain timedue to mismatch of a monitoring band, i.e., CSB, the terminal mayoperate as DRX Off or cause a problem in the HARQ timeline.

According to the operations shown in FIGS. 54 and 55 , it is possible toreduce the problem of L1 signal reception error by not using the BWreduction instruction control signal. That is, the terminal can operatein a wideband, CSB #2, only during a specific duration after the BWexpansion, and then return to a narrowband, CSB #1.

Referring to FIG. 54 , the base station also notifies, to the terminal,a duration 5440 for monitoring CSB #2 as well as a CSB #2 location 5420through a BW expansion instruction control signal 5430 in CBS #1 5410.

On the other hand, the base station may configure in advance theduration information for maintaining a wideband by means of the RRCparameter instead of the L1 signal, considering the capacity andperformance of the L1 signal. However, compared to case of using the L1signal, dynamic control may be limited in case of configuring by RRC inadvance. Therefore, when using the RRC parameter, a timer may be useful,like the existing DRX inactivity timer, rather than a fixed duration.

FIGS. 55 to 58 are diagrams illustrating examples of BW expansion andreduction operation by physical layer and radio resource control (RRC)control signals according to various embodiments of the disclosure.

Referring to FIG. 55 , the terminal monitors CSB #2 indicated by a BWexpansion instruction control signal 5530 in CBS #1 5510 and then startsan RRC configured timer 5540 because of failing to receive a DL signalfrom the next CSB #2 5520 subframe. If the timer expires after 3subframes without receiving the DL signal, the terminal returns to anarrow band CSB #1 in the next subframe. The start time of the timer maybe changed.

If the timer value is set to be small, the terminal may not continuouslyreceive a base station signal due to deterioration of a channel qualityeven though a control signal of the base station is actually transmittedto the terminal. In this situation, there may occur a band mismatch thatthe base station transmits a signal in a wide band and the terminaltries to receive a signal in a narrow band. The base station may start atimer from a time when feedback of the terminal or a scheduled UL signaldoes not arrive or when an event of no UL signal arrival satisfies agiven condition. When the timer of the base station expires, the basestation transmits a base station signal through a narrow band controlchannel, i.e., CSB #1. In order to support this operation, the positionof the on-duration for the narrow band control channel of the terminalmay be predetermined. That is, the start of the operation in a wide bandmay depend on the L1/MAC signal, and the control channel receptionoperation in a narrow band may follow the DRX cycle determined based onthe system time like the conventional DRX operation. When a wide bandinactivity timer expires according to the inactivity of a controlchannel in a wide band, the terminal retunes to a narrow band andreceives the control channel according to the configured DRXon-duration.

On the other hand, the interpretation of inactivity may be applieddifferently depending on cases.

Referring to FIG. 56 , the terminal switches to a wide band 5610 inresponse to a BW expansion indication control signal 5620 and thenreceives a BW reduction indication control signal 5630 of the basestation in the next subframe. This is because the base station hasdetermined that there is no more traffic to be transmitted through awide band.

Even if the terminal monitors a narrow band CSB #1, an RRC configuredinactivity timer 5650 may be maintained without expiration. That is, ina state where the terminal does not receive a DL resource allocationcontrol signal in a wide band, i.e., CSB #2, the terminal operation ofswitching between a wide band and a narrow band in response to a controlsignal of the base station or a certain rule may affect the inactivitytimer. The terminal may stop the timer only after receiving the DLresource allocation control signal through the CSB #2 in a wide band.

Referring to FIG. 57 illustrated is an operation in which after a timer5710 starts, the timer expires when a base station signal issuccessfully received through a wide band CSB #2 5730 during the BWswitching of the terminal, and a second timer 5720 starts when a DLsignal is not received in the subsequent subframe.

Referring to FIG. 58 , in order to avoid complicated operations as shownin FIGS. 56 and 57 , according to an embodiment, the base station mayconfigure a pattern 5810 of switching between a wide band and a narrowband through RRC after the wide band switching of the terminal. The basestation may instruct the terminal on the first narrow band switchingthrough the L1 control signal 5820 or the RRC signal as in otherembodiments. When controlling with RRC, the position should bedetermined based on SFN and subframe. If the BW switching is not urgent,the L1 control signal may be replaced with MAC command elements (CEs).In this case, the MAC CE should include absolute position informationinstead of relative interval information.

The pattern of BW switching may be configured as an absolute positionwith respect to the SFN and the subframe or as a position relative tothe position specified with the L1 control signal. Also, a subframe inwhich a pattern is valid may be limited to a subframe corresponding toDRX on-duration or a subframe before a DRX cycle timer expires. Inaddition, through the MAC CE, the base station may instruct the terminalto switch to which BW.

When the base station instructs the BW switching operation using aphysical layer signal or an RRC control signal, the setup by an L1control signal may take priority over the setup by an RRC control signalfor dynamic setup. However, considering a case where a stable terminaloperation is difficult due to a plurality of L1 control signals, thesetup by an RRC control signal always precedes the setup by an L1control signal in a subframe of a predetermined position (period,offset).

Meanwhile, independent of the BW control operation by a physical layersignal, the C-DRX of LTE, i.e., the connected DRX operation, can bemodified to be associated with the BW control. A method using C-DRX mayoperate alone or may be operated together with the operation ofcontrolling the BW through a physical layer signal. Specific details aredescribed in below with reference to FIG. 59 .

FIGS. 59 and 60 are diagrams illustrating examples of connected mode DRX(C-DRX) operation for adaptive BW according to various embodiments ofthe disclosure.

According to the LTE DRX configuration, one DRX cycle is divided into anon-duration and an off-duration. Similarly, referring to FIG. 59 , thebase station may divide one DRX cycle into a wide band on-duration 5910,a narrow band on-duration 5920, and an off-duration 5930. For thisscheme, the base station only needs to notify the terminal aboutadditional on-duration information for each band in the DRXconfiguration information. However, if there are variety of graduallyreduced sizes of bands, it may take a considerable time for the terminalto transition to the complete off-state.

Referring to FIG. 60 , according to another embodiment, the terminal mayoperate in a band-specific DRX cycle in which durations for monitoring awide band and a narrow band may be configured differently in time. Thisis similar to an operation in LTE C-DRX of switching to the long DRXcycle when a certain number of cycles are required in the short DRXcycle. Therefore, the base station may configure information per DRXcycle (DRX cycle, on-duration, DRX cycle timer, etc.) 6010 to 6060according to bands to be switched, and a band switching rule may beincluded in the C-DRX configuration. For example, this may berepresented in the order of Band #1, Band #2, Band #3, and the like orthe order of CSB #1, CSB #2, CSB #3, and the like.

Alternatively, according to an embodiment, the order of band switchingmay be entrusted entirely to the physical layer. In this case, theterminal operates with a common DRX cycle and a DRX cycle timer, and BWand CSB are determined according to the L1 control signal. The terminalmay inquire about the BW to be changed to L1 before one DRX cycle timerexpires.

Alternatively, in the RRC connection setup or RRC connectionreestablishment process, the terminal may request the L1 to set aplurality of BWs (CSBs) and their order. The terminal switches the BW(CSB) according to the order as one DRX cycle timer expires or the DRXcycle ends. If the terminal expands the BW again according to a BWreconfiguration control signal of the base station or according to acondition preconfigured in the terminal, the BW (CSB) is switched againfrom the expanded BW in the order. When the DRX cycle or the DRX cycletimer for the minimum BW (CSB) expires after all BWs (CSBs) have beenswitched, the terminal a) switches to the long DRX while maintaining theminimum BW (CSB), b) switches to the long DRX by switching to BW (CSB)for separately configured long DRX, or c) switches to the idle DRX.

On the other hand, without introducing a new C-DRX configuration, it ispossible to maintain the existing LTE C-DRX configuration and operationand to control the BW change operation with additional L1 setup.According to an embodiment, the C-DRX configuration to be controlled bythe RRC is the same, but the base station may configure information (BW,SRB, number of subframes, etc.) for BW switching in the on-duration byusing the L1 signal. According to another embodiment, the base stationmay configure information (BW, SRB, etc.) for BW switching, which isreduced each time a short DRX cycle is encountered, by using the L1signal. According to still another embodiment, the base station mayconfigure the BW connected to the short DRX cycle and the BW connectedto the long DRX cycle by using the L1 signal.

The modified operation of the C-DRX assumes that there are differentparameters for BWs in one DRX configuration. On the other hand,different DRX configurations for BWs may be possible for more free DRXconfiguration. In this case, the terminal should operate while reviewinga plurality of DRX configurations at the same time, and it is necessaryto determine which DRX configuration has a priority according to apredetermined rule in order to prevent confusion of operation accordingto a plurality of DRX configurations.

FIG. 61 is a diagram illustrating an example of DRX setup for a wideband and a narrow band according to an embodiment of the disclosure.

Referring to FIG. 61 , illustrated is a state where wide band DRXs 6110and 6115 and narrow band DRXs 6120 and 6125 are configured,respectively. The terminal receives the DRX configurations for two bandsand has to follow one of two DRX configurations for a subframe in whicha conflict operation occurs. If power consumption is emphasized, theterminal may prefer narrow band DRX configuration rather than wide bandDRX configuration.

FIGS. 62 and 63 are diagrams illustrating examples of DRX setup and apriority rule for a wide band and a narrow band according to variousembodiments of the disclosure.

Referring to FIG. 62 , illustrated is an operation in which when a wideband on-duration 6210 and a narrow band on-duration 6220 are bothconfigured in one subframe, the terminal follows the narrow bandon-duration configuration 6210 and monitors a DL signal by configuring anarrow band CSB #1.

Referring to FIG. 63 , on the other hand, in case where the datatransmission amount is more important, FIG. 63 shows an operation inwhich when a wide band on-duration 6310 and a narrow band on-duration6320 are both configured in one subframe, the terminal follows the wideband on-duration configuration 6310 and monitors a DL signal byswitching to a wide band CSB #2. In order to support differentconfigurations as shown in FIGS. 62 and 63 , the base station mayfurther configure priority information between DRXs for bands to theterminal through RRC.

If a DL signal is not received in the DRX configuration for each bandand its operation, the terminal starts an inactivity timer. If theinactivity timer for each band is set, the terminal a) may start theinactivity timer for a corresponding band when the DL signalcorresponding to the band is not received, or b) may start theinactivity timer for each band when the DL signal corresponding to theband is not received.

If the inactivity timer is set to a single value regardless of band, acondition for determining the DRX inactivity may be determined as atleast one of the following: 1) to start the inactivity timer only whenno DL signal is received in all bands (all configured CSBs), or 2) tostart the inactivity timer only when the DL signal corresponding to theband (CSB) selected by the priority is not received.

In the disclosure, the type of a DL signal to be monitored in relationto the DRX operation is determined in the standard or can be configuredby the base station. If a DL signal, to be not monitored in relation tothe DRX operation, is received, it may be regarded that the DL signal isnot received in the DRX operation.

In the BW adaptation and power saving procedures proposed in thedisclosure, configuration of associating one or more bands configuredfor scheduling with the DRX procedure is further required.

Depending on various embodiments proposed, the configuration schemeassociated with the DRX procedure may be varied. Respective embodimentsare largely classified as follows, and the DRX procedure associationconfiguration may be varied depending on such classification.

A. In case where the timing when the terminal switches from band 1 toband 2 depends on the L1/MAC signal of the base station, and the timingwhen switching from band 2 to band 1 also follows the L1/MAC signal ofthe base station:

Since the band ID is included in the L1/MAC signal, there is noconnection with a separate DRX configuration. That is, the DRX operatesin common regardless of the band. However, when a reception error of theL1/MAC signal of the base station occurs, the base station may configurea specific band (e.g., band 1) for the fallback operation. At this time,the base station may include the fallback band in the DRX configuration.

B. In case where the timing when the terminal switches from band 1 toband 2 depends on the L1/MAC signal of the base station, and the timingwhen switching from band 2 to band 1 follows the inactivity timer:

When the terminal switches from band 1 to band 2, there is no need toconfigure band 2 associated with the DRX. However, when switching fromband 2 to band 1, the base station configures the DRX to be operated inband 1 because it follows the timer. The terminal should follow theinactivity timer of band 2 after switching to band 2, and may beconfigured by the base station to be operated according to one of 1)using the inactivity timer of the DRX in common, 2) using the inactivitytimer configured separately for band 2, 3) using the inactivity timer ofthe DRX with a scale value, or 4) using the inactivity timer configuredseparately for band 1 with a scale value. The scale value may beindicated by a DRX configuration or a separate configuration.

C. In case where the switching from band 1 to band 2 depends on theL1/MAC signal of the base station (but the control channel receptiontiming is configured separately), and the switching from band 2 to band1 also depends on the L1/MAC signal of the base station (but the controlchannel reception timing is configured separately):

In this case, the DRX cycle and on-duration common to bands or for eachband should be configured. In case of being common to bands, no separateband configuration is required for DRX configuration. If the DRX isconfigured for each band, configuration is performed by at least one ofmethods for 1) matching the DRX configuration with the number of bandsand indicating a band in each DRX configuration, 2) setting one DRXconfiguration and indicating bands for operations of on-duration andoff-duration included in the DRX configuration, 3) setting one DRXconfiguration and indicating a band for each of the short DRX cycle andthe long DRX cycle included in the DRX configuration, or 4) setting oneDRX configuration and indicating a band for each of the on-duration, theshort DRX cycle, and the long DRX cycle included in the DRXconfiguration.

In the setup and procedure proposed in the disclosure, the Layer 2 ofthe terminal may not need to know the actual position and size of aband. That is, the physical information of a band is not visible at theLayer 2, but the logical position and size can be set. The Layer 2 mayconstruct a control channel or transport channel, based on logical bandposition/size information. Also, the terminal may manage BW informationin a list for DRX operation and display it by index.

In examples proposed in the disclosure, it has been assumed that mostterminals cannot simultaneously monitor narrow band and wide band BWs.However, depending on the capability of the terminal, narrow band andwide band BWs can be monitored at the same time in some cases.

Meanwhile, the BW provided through the L1 signal and the maximum BW ofthe terminal according to the terminal capability may be different.Accordingly, when a plurality of BW-specific DRX configurations arereceived, the terminal may operate simultaneously in the on-duration ofone or more BW-specific DRX configurations within the maximum BW of theterminal capability. The on-duration of the DRX configuration exceedingthe maximum BW of the terminal capability is excluded from monitoring.For this operation, the priority of the BW-specific DRX configurationmay be configured to the terminal by the base station.

FIG. 64 is a flow diagram illustrating an operation of a terminalaccording to an embodiment of the disclosure.

Referring to FIG. 64 , during the RRC connection setup procedure S6410,the terminal requests and acquires information about the position of anoperation BW or control sub-band (CSB) from the physical layer atoperations S6420 and S6430.

At operation S6440, based on the acquired information, or by reportingthe acquired information to the base station, the terminal receives DRXconfiguration per BW or configuration for parameters per BW in DRX fromthe base station.

When the connection is completed, the terminal starts an operation forshort DRX in C-DRX. The terminal performs PDCCH monitoring for eachsubframe to receive a control signal of the base station at operationS6450. Then, at operation S6460, the terminal determines whether thereception of a DL signal is successful.

If the reception of a DL signal is successful, the terminal continuouslyperforms PDCCH monitoring. In a certain scenario, there may be cases inwhich, despite successful PDCCH monitoring, another BW or CSB ismonitored under L1 control or RRC control.

If a DL signal is not received as a result of the PDCCH monitoring, theterminal updates the DRX parameters such as the inactivity timer and theDRX cycle timer at operation S6465. If the BW switching is requiredsince a condition of the inactivity timer or the BW switching timer issatisfied at operation 6470, the terminal checks at operation S6475whether it meets a short DRX termination condition. This conditioncorresponds, for example, a case where the PDCCH monitoring fails at theminimum BW and thus there is no further BW to be reduced or a case wherethe short DRX cycle timer expires.

If the short DRX termination condition is not satisfied at operation6470, the terminal decreases the BW at operation S6480 and resumes theshort DRX operation.

If the short DRX termination condition is satisfied, the terminal startsthe long DRX at operation S6485. The long DRX operation is performed atthe minimum or configured BW, and is similar generally to the LTE longDRX operation. The terminal monitors the PDCCH according to the long DRXat operation S6490. If a DL signal is not successfully received atoperation S6491, the terminal determines at operation S6492 whether thelong DRX termination condition is satisfied. If the long DRX terminationcondition is satisfied, the terminal switches to the idle mode atoperation S6493.

-   -   Method for separately setting a condition for determining        inactivity in wideBWP:

The BW adaptation or switching operation of the disclosure is differentfrom the SCell addition/release in the existing CA, as follows. In theCA, the PCell is always activated, and the terminal monitors the PCell.However, in case of BW switching, the terminal should transmit andreceive control signals such as an RRC signal and MAC CE to and from thebase station, even though moving in any band. Therefore, even if theterminal switches from one band (band 1) to another band (band 2) andthere is no data traffic in band 2, the terminal can receive the RRC/MACcontrol signal of the base station. However, receiving the RRC/MACcontrol signal of the base station in band 2, which is a narrow band,affects the power consumption of the terminal Therefore, whendetermining the inactivity in the band 2, the terminal may operate by 1)not reflecting the control channel activity for transmitting only theRRC/MAC control signal of the base station in the inactivity timeroperation, 2) reflecting only the scheduling assignment below certainphysical resource block (PRB) in the inactivity timer operation, 3)reflecting in the inactivity timer operation when a base station signalof a certain number of times (or a certain amount of transmission) isreceived within a certain duration, 4) reflecting in the inactivitytimer operation only for a specific DCI format, or 5) determiningwhether to reflect in the inactivity timer operation through a separateinstruction of the base station.

-   -   Dual timer setup:

Described above is the timer operation for switching from a wide band toa narrow band. Switching from a narrow band to a wide band may beindicated by the DCI/MAC signal of the base station. However, when anerror occurs in reception of the DCI/MAC signal, the terminal shouldswitch from a wide band to a narrow band for a fallback. However, thebase station may set a timer value differently because the requirementsof two cases may be different. That is, when the DCI/MAC signal forswitching from a narrow band to a wide band is received duringmonitoring, the terminal starts timer #1. If the terminal does notreceive a base station signal in the wide band until the expiration ofthe timer #1 while performing the band switching operation, the terminalreturns to a narrow band.

On the other hand, the terminal that succeeds in receiving a basestation signal in a wide band and then does not receive a base stationsignal after the end of the on-duration starts timer #2. When the timer#2 expires, the terminal switches to a narrow band. In general, it isadvantageous that the value of timer #1 is shorter than the value oftimer #2 because of fast fallback in case of error.

FIG. 65 shows a DRX operation for a TTI change according to anembodiment of the disclosure.

Referring to FIG. 65 , a transmit time interval (TTI) refers to a timerequired to transmit one or more transport blocks (TBs) and is oftenused as a basic time unit for performing scheduling and HARQ operationsin the MAC. The terminal receives TTI information in advance in theinitial access procedure or receives default TTI and BW informationthrough the SI.

For example, a normal TTI having a length of 1 ms may be set as a basicTTI. Further, during the random access procedure or after the completionof the RRC connection setup, the terminal may receive additional TTI andBW information through the RRC message. For example, the additional TTImay be set to a short TTI of 0.5 ms in length.

Parameters for expressing the DRX operation in LTE are represented inunits of subframes. Referring to a normal TTI case 6510 of FIG. 65 , itcan be seen that the on-duration is represented by 2 ms and the DRXcycle is represented by 6 ms.

When the same DRX parameter expression scheme as LTE is directlyimported to 5G, the TTI is set to the short TTI as shown in short TTIcase A 6520, and the terminal monitors PDCCH during the on-duration of 2ms within the same DRX cycle (6 ms). While in the normal TTI case thenumber of PDCCH monitoring is twice in the same on-duration (2 ms), inthe short TTI case A the TTI length is reduced to half and thus thenumber of PDCCH monitoring increases to four times. However, the powerconsumption of the terminal may be increased because the same PDCCHmonitoring opportunity is not maintained.

In short TTI case B 6530, the on-duration is reduced from 2 ms to 1 msaccording to the reduced TTI, and the number of PDCCH monitoring is alsoreduced to twice within one on-duration. However, because the DRX cycleis also reduced from 6 ms to 3 ms according to the reduced TTI, fourPDCCH monitoring times are still set for the same time as the normal TTIcase. Therefore, the power consumption of the terminal is unvariedbetween the short TTI case A 6520 and the short TTI case B 6530.

Therefore, the disclosure proposes the following method. That is, amongthe DRX parameters, timers (on-duration, inactivity timer, etc.) relatedto PDCCH monitoring are represented by TTI, and other parameters arerepresented by subframe.

Referring to short TTI case C 6540, the on-duration is reduced from 2 msto 1 ms in comparison with the normal TTI, and the number of PDCCHmonitoring is also maintained as twice in one on-duration. In addition,the number of PDCCH monitoring is kept twice in comparison with thenormal TTI within DRX cycle 6 ms. In detail, on-duration, inactivitytimer, ULRetransmissionTimer, StartOffset, and the like can berepresented by TTI, whereas DRX cycle, shortCycleTimer, and the like canbe represented by a subframe.

The TTI length may be set by means of SI or RRC, but additional TTI orPDCCH resource settings may be performed in the physical layer L1 forconvenience of dynamic scheduling. However, if the TTI lengthdynamically changes according to the additional TTI/PDCCH resourcesetting, a delay may occur in recalculating the timer on the L2 layer.This delay may cause a problem when a scheduling/HARQ operation occursin a short TTI. Therefore, the disclosure proposes a method of notincluding the TTI dynamically changed according to the L1 signal intothe MAC timer calculation. According to an embodiment, the variationwithin the specific time length set through the RRC is not included inthe MAC timer calculation, and the variation longer than the specifictime length may be included in the MAC timer calculation.

According to an embodiment, the base station may set an RRC message tothe terminal to define which length of TTI for a specific timer. Forexample, the on-duration may be set to a shortest TTI (0.25 ms), theinactivity timer may be set to a shorter TTI (0.5 ms), and the DRX cyclemay be set to a normal TTI (1.0 ms). Also, some parameters may bepre-specified in the standard. For example, the on-duration may dependon the length of a mini-slot set in L1, and the DRX cycle may bespecified to follow the length of a slot set in L1.

According to an embodiment, some of the parameters required for the DRXprocedure may be fixed in time units, while others may be set to changetime units according to numerology. The base station may fix the DRXcycle, shortCycleTimer, etc. in units of subframes. The on-duration,inactivity timer, ULRetransmissionTimer, and StartOffset may beexpressed in units of [slot, mini-slot], and which unit will be used maybe determined depending on any combination of a control channel, band,index in DCI, and TTI which are set by the base station. For example, ifthe terminal receives a control channel in band 1 for eMBB, theon-duration value 4 is regarded as 4 slots, and if the terminal receivesa control channel in band 2 for URLLC, the same on-duration value 4 isunderstood as 4 mini-slots.

FIG. 66 is a diagram illustrating an example of determining a TTI valuebased on to a control channel monitoring periodicity and a transmissionduration according to an embodiment of the disclosure.

Referring to FIG. 66 , according to the control channel monitoringperiodicity and the transmission duration, the values of TTI may bedetermined differently depending on the situation.

In cases (a) and (b) 6610 and 6620 in FIG. 66 , a data channel isallocated only within a control channel observation period, so that thetransmission period of scheduling is equal to the control channelobservation period. Therefore, the TTI is equal to the control channelobservation period. However, in case (c) 6630 of FIG. 66 , thetransmission duration is indicated to be longer than the control channelobservation period, so that the transmission period of scheduling isambiguous.

This may be varied depending on the control of the base station. If thebase station instructs the terminal on a transmission block having atransmission duration longer than the control channel observation periodso as not to observe overlapped control channels, the TTI is equal tothe indicated transmission duration. However, if the base stationinstructs the terminal to observe the control channel observation periodeven during the transmission duration, the base station may schedule theterminal every control channel observation period. Therefore, in thiscase, the TTI is the same as the control channel observation period.

Detailed embodiments regarding an operation of switching bands on thebasis of a timer as shown in FIGS. 54, 55, 56 and 60 will be describedbelow. This timer may be a new timer such as a band switching timer or aband validity timer, or may be an existing timer such as a drxinactivity timer or a DRX short cycle timer.

FIG. 67 is a diagram illustrating a timer-based band switching operationaccording to various embodiments of the disclosure.

Embodiment 4-1

Referring to FIG. 67 , the embodiment 4-1 shows an operation procedurethat supports case A 6710.

A MAC entity may be configured to have a DRX function for controllingthe PDCCH monitoring of the UE by the RRC. If the DRX is configured whenthe UE is in the RRC_CONNECTED state, the MAC entity may discontinuouslymonitor the PDCCH according to the described DRX operation. When usingthe DRX operation, the MAC entity should monitor the PDCCH by using aspecific band at a specific time according to the specific requirements.At least one of the following parameters is configured for the DRXoperation: drx_BandIndex, onDurationTimer, drx-InactivityTimer,drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle,drxStartOffset, drxShortCycleTimer, shortDRX-Cycle.

The drx_BandIndex related to the band may be included in the DRXconfiguration or may be defined with an index of the band configured asa default band or a primary band in the band configuration included inthe RRC Connection(re-)Configuration procedure without being included inthe DRX configuration.

For example, it may be indicated as drx_BandIndex=defaultBandIndex, ordrx_BandIndex=primaryBandIndex.

If the DRX cycle is configured, the MAC entity of the UE operates inactive time in case of the follows:

-   -   when at least one of onDurationTimer, drx-InactivityTimer,        drx-RetransmissionTimer, drx-ULRetransmissionTimer, and        mac-ContentionResolutionTimer is running,    -   when scheduling request (SR) is sent to PUCCH and pending,    -   when a UL grant for unsent HARQ retransmission can occur, and    -   when a control signal is generated for the first transmission on        the PDCCH after receiving the RAR.

If the DRX is configured, the MAC entity of the UE performs thefollowings in every subframe (or slot, symbol, or time unit set by RRC).

-   -   When DRX Command MAC CE or Long DRX Command MAC CE is received,

stop onDurationTimer and drx-Inactivity Timer.

-   -   When the drx-Inactivity Timer expires or the DRX Command MAC CE        is received,        -   if the short DRX cycle is configured, (re)start the            drxShortCycleTimer and use the short DRX cycle.        -   if the short DRX cycle is not configured, use the long DRX            cycle.    -   When the drxShortCycleTimer expires, use the long DRX cycle.    -   When the drxShortCycleTimer has not expired and when the Long        DRX Command MAC CE is received,

stop the drxShortCycleTimer and use the long DRX cycle.

-   -   When the UE is using the short DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe        number]modulo(shortDRX-Cycle)=(drxStartOffset)modulo(shortDRX-Cycle).    -   When the UE is using the long DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe number]modulo(longDRX-Cycle)=drxStartOffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot,symbol, or time unit set by RRC) in which the PDCCH is present in ActiveTime, and in a band indicated by the drx_BandIndex. If the PDCCHindicates DL transmission in this subframe, or if a DL assignment is setin this subframe, the UE starts the HARQ RTT timer for the correspondingHARQ process and stops the drx-RetransmissionTimer for the same HARQprocess.

If the PDCCH indicates UL transmission in this subframe, or if an ULgrant is set in this subframe, the UE starts the UL HARQ RTT timer forthe HARQ process of the subframe including the last retransmission ofcorresponding PUSCH transmission. Also, the UE stops theDRX_ULRetransmissionTimer for the same HARQ process.

If the PDCCH indicates a new transmission, the UE (re)starts thedrx-InactivityTimer.

Embodiment 4-2

The embodiment 4-2 shows an operation procedure that supports case B6720 in FIG. 67 .

A MAC entity may be configured to have a DRX function for controllingthe PDCCH monitoring of the UE by the RRC. If the DRX is configured whenthe UE is in the RRC_CONNECTED state, the MAC entity may discontinuouslymonitor the PDCCH according to the described DRX operation. When usingthe DRX operation, the MAC entity should monitor the PDCCH by using aspecific band at a specific time according to the specific requirements.At least one of the following parameters is configured for the DRXoperation: onDurationTimer, drx-InactivityTimer,drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle,drxStartOffset, drx_BandIndex_longDRX-Cycle, drxShortCycleTimer,shortDRX-Cycle.

The drx_BandIndex_longDRX-Cycle related to the band may be included inthe DRX configuration or may be defined with an index of the bandconfigured as a default band or a primary band in the band configurationincluded in the RRC Connection(re-)Configuration procedure without beingincluded in the DRX configuration.

For example, it may be indicated asdrx_BandIndex_longDRX-Cycle=defaultBandIndex, ordrx_BandIndex_longDRX-Cycle=primaryBandIndex.

If the DRX cycle is configured, the MAC entity of the UE operates inactive time in case of the follows:

-   -   when at least one of onDurationTimer, drx-InactivityTimer,        drx-RetransmissionTimer, drx-ULRetransmissionTimer, and        mac-ContentionResolutionTimer is running,    -   when scheduling request (SR) is sent to PUCCH and pending,    -   when a UL grant for unsent HARQ retransmission can occur, and    -   when a control signal is generated for the first transmission on        the PDCCH after receiving the RAR.

If the DRX is configured, the MAC entity of the UE performs thefollowings in every subframe (or slot, symbol, or time unit set by RRC).

-   -   When DRX Command MAC CE or Long DRX Command MAC CE is received,

stop onDurationTimer and drx-Inactivity Timer.

-   -   When the drx-Inactivity Timer expires or the DRX Command MAC CE        is received,        -   if the short DRX cycle is configured, (re)start the            drxShortCycleTimer and use the short DRX cycle.        -   if the short DRX cycle is not configured, use the long DRX            cycle.    -   When the drxShortCycleTimer expires, use the long DRX cycle.    -   When the drxShortCycleTimer has not expired and when the Long        DRX Command MAC CE is received,

stop the drxShortCycleTimer and use the long DRX cycle.

-   -   When the UE is using the short DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe        number]modulo(shortDRX-Cycle)=(drxStartOffset)modulo(shortDRX-Cycle).    -   When the UE is using the long DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe number]modulo(longDRX-Cycle)=drxStartOffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot,symbol, or time unit set by RRC) in which the PDCCH is present in ActiveTime, and in a band indicated by the drx_BandIndex_longDRX-Cycle if thelong DRX cycle is used. If the PDCCH indicates DL transmission in thissubframe, or if a DL assignment is set in this subframe, the UE startsthe HARQ RTT timer for the corresponding HARQ process and stops thedrx-RetransmissionTimer for the same HARQ process.

If the PDCCH indicates UL transmission in this subframe, or if an ULgrant is set in this subframe, the UE starts the UL HARQ RTT timer forthe HARQ process of the subframe including the last retransmission ofcorresponding PUSCH transmission. Also, the UE stops theDRX_ULRetransmissionTimer for the same HARQ process.

If the PDCCH indicates a new transmission, the UE (re)starts thedrx-InactivityTimer.

Embodiment 4-3

The embodiment 4-3 shows an operation procedure that supports both caseA 6710 and case B 6720 in FIG. 67 .

A MAC entity may be configured to have a DRX function for controllingthe PDCCH monitoring of the UE by the RRC. If the DRX is configured whenthe UE is in the RRC_CONNECTED state, the MAC entity may discontinuouslymonitor the PDCCH according to the described DRX operation. When usingthe DRX operation, the MAC entity should monitor the PDCCH by using aspecific band at a specific time according to the specific requirements.At least one of the following parameters is configured for the DRXoperation: onDurationTimer, drx-InactivityTimer,drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle,drxStartOffset, drx_BandIndex_longDRX-Cycle, drxShortCycleTimer,shortDRX-Cycle, drx_BandIndex_shortDRX-Cycle.

The drx_BandIndex_longDRX-Cycle or the drx_BandIndex_shortDRX-Cyclerelated to the band may be included in the DRX configuration or may bedefined with an index of the band configured as a default band or aprimary band in the band configuration included in the RRCConnection(re-)Configuration procedure without being included in the DRXconfiguration.

For example, it may be indicated asdrx_BandIndex_shortDRX-Cycle=defaultBandIndex, ordrx_BandIndex_longDRX-Cycle=primaryBandIndex.

If the DRX cycle is configured, the MAC entity of the UE operates inactive time in case of the follows:

-   -   when at least one of onDurationTimer, drx-InactivityTimer,        drx-RetransmissionTimer, drx-ULRetransmissionTimer, and        mac-ContentionResolutionTimer is running,    -   when scheduling request (SR) is sent to PUCCH and pending,    -   when a UL grant for unsent HARQ retransmission can occur, and    -   when a control signal is generated for the first transmission on        the PDCCH after receiving the RAR.

If the DRX is configured, the MAC entity of the UE performs thefollowings in every subframe (or slot, symbol, or time unit set by RRC).

-   -   When DRX Command MAC CE or Long DRX Command MAC CE is received,

stop onDurationTimer and drx-Inactivity Timer.

-   -   When the drx-Inactivity Timer expires or the DRX Command MAC CE        is received,        -   if the short DRX cycle is configured, (re)start the            drxShortCycleTimer and use the short DRX cycle.        -   if the short DRX cycle is not configured, use the long DRX            cycle.    -   When the drxShortCycleTimer expires, use the long DRX cycle.    -   When the drxShortCycleTimer has not expired and when the Long        DRX Command MAC CE is received,

stop the drxShortCycleTimer and use the long DRX cycle.

-   -   When the UE is using the short DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe        number]modulo(shortDRX-Cycle)=(drxStartOffset)modulo(shortDRX-Cycle).    -   When the UE is using the long DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe number]modulo(longDRX-Cycle)=drxStartOffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot,symbol, or time unit set by RRC) in which the PDCCH is present in ActiveTime, and in a band indicated by the drx_BandIndex_shortDRX-Cycle if theshort DRX cycle is used, or in a band indicated by thedrx_BandIndex_longDRX-Cycle if the long DRX cycle is used. If the PDCCHindicates DL transmission in this subframe, or if a DL assignment is setin this subframe, the UE starts the HARQ RTT timer for the correspondingHARQ process and stops the drx-RetransmissionTimer for the same HARQprocess.

If the PDCCH indicates UL transmission in this subframe, or if an ULgrant is set in this subframe, the UE starts the UL HARQ RTT timer forthe HARQ process of the subframe including the last retransmission ofcorresponding PUSCH transmission. Also, the UE stops theDRX_ULRetransmissionTimer for the same HARQ process.

If the PDCCH indicates a new transmission, the UE (re)starts thedrx-InactivityTimer.

Embodiment 4-4

The embodiment 4-4 shows an operation procedure that supports case B6720 in FIG. 67 .

A MAC entity may be configured to have a DRX function for controllingthe PDCCH monitoring of the UE by the RRC. If the DRX is configured whenthe UE is in the RRC_CONNECTED state, the MAC entity may discontinuouslymonitor the PDCCH according to the described DRX operation. When usingthe DRX operation, the MAC entity should monitor the PDCCH by using aspecific band at a specific time according to the specific requirements.At least one of the following parameters is configured for the DRXoperation: onDurationTimer, drx-InactivityTimer,drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle,drxStartOffset, drx_BandIndex_longDRX-Cycle, drxShortCycleTimer,shortDRX-Cycle.

The drx_BandIndex_longDRX-Cycle related to the band may be included inthe DRX configuration or may be defined with an index of the bandconfigured as a default band or a primary band in the band configurationincluded in the RRC Connection(re-)Configuration procedure without beingincluded in the DRX configuration.

For example, it may be indicated asdrx_BandIndex_longDRX-Cycle=defaultBandIndex, ordrx_BandIndex_longDRX-Cycle=primaryBandIndex.

If the DRX cycle is configured, the MAC entity of the UE operates inactive time in case of the follows:

-   -   when at least one of onDurationTimer, drx-InactivityTimer,        drx-RetransmissionTimer, drx-ULRetransmissionTimer, and        mac-ContentionResolutionTimer is running,    -   when scheduling request (SR) is sent to PUCCH and pending,    -   when a UL grant for unsent HARQ retransmission can occur, and    -   when a control signal is generated for the first transmission on        the PDCCH after receiving the RAR.

If the DRX is configured, the MAC entity of the UE performs thefollowings in every subframe (or slot, symbol, or time unit set by RRC).

-   -   When DRX Command MAC CE or Long DRX Command MAC CE is received,

stop onDurationTimer and drx-Inactivity Timer.

-   -   When the drx-Inactivity Timer expires or the DRX Command MAC CE        is received,        -   if the short DRX cycle is configured, (re)start the            drxShortCycleTimer and use the short DRX cycle.        -   if the short DRX cycle is not configured, use the long DRX            cycle and use a band indicated by the            drx_BandIndex_longDRX-Cycle.    -   When the drxShortCycleTimer expires, use the long DRX cycle and        use a band indicated by the drx_BandIndex_longDRX-Cycle.    -   When the drxShortCycleTimer has not expired and when the Long        DRX Command MAC CE is received,

stop the drxShortCycleTimer, use the long DRX cycle, and use a bandindicated by the drx_BandIndex_longDRX-Cycle.

-   -   When the UE is using the short DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe        number]modulo(shortDRX-Cycle)=(drxStartOffset)modulo(shortDRX-Cycle).    -   When the UE is using the long DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe number]modulo(longDRX-Cycle)=drxStartOffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot,symbol, or time unit set by RRC) in which the PDCCH is present in ActiveTime. If the PDCCH indicates DL transmission in this subframe, or if aDL assignment is set in this subframe, the UE starts the HARQ RTT timerfor the corresponding HARQ process and stops the drx-RetransmissionTimerfor the same HARQ process.

If the PDCCH indicates UL transmission in this subframe, or if an ULgrant is set in this subframe, the UE starts the UL HARQ RTT timer forthe HARQ process of the subframe including the last retransmission ofcorresponding PUSCH transmission. Also, the UE stops theDRX_ULRetransmissionTimer for the same HARQ process.

If the PDCCH indicates a new transmission, the UE (re)starts thedrx-InactivityTimer.

Embodiment 4-5

The embodiment 4-5 shows an operation procedure that supports both caseA 6710 and case B 6720 in FIG. 67 .

A MAC entity may be configured to have a DRX function for controllingthe PDCCH monitoring of the UE by the RRC. If the DRX is configured whenthe UE is in the RRC_CONNECTED state, the MAC entity may discontinuouslymonitor the PDCCH according to the described DRX operation. When usingthe DRX operation, the MAC entity should monitor the PDCCH by using aspecific band at a specific time according to the specific requirements.At least one of the following parameters is configured for the DRXoperation: onDurationTimer, drx-InactivityTimer,drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle,drxStartOffset, drx_BandIndex_longDRX-Cycle, drxShortCycleTimer,shortDRX-Cycle, drx_BandIndex_shortDRX-Cycle.

The drx_BandIndex_longDRX-Cycle or the drx_BandIndex_shortDRX-Cyclerelated to the band may be included in the DRX configuration or may bedefined with an index of the band configured as a default band or aprimary band in the band configuration included in the RRCConnection(re-)Configuration procedure without being included in the DRXconfiguration. For example, it may be indicated asdrx_BandIndex_shortDRX-Cycle=defaultBandIndex, ordrx_BandIndex_longDRX-Cycle=primaryBandIndex.

If the DRX cycle is configured, the MAC entity of the UE operates inactive time in case of the follows:

-   -   when at least one of onDurationTimer, drx-InactivityTimer,        drx-RetransmissionTimer, drx-ULRetransmissionTimer, and        mac-ContentionResolutionTimer is running,    -   when scheduling request (SR) is sent to PUCCH and pending,    -   when a UL grant for unsent HARQ retransmission can occur, and    -   when a control signal is generated for the first transmission on        the PDCCH after receiving the RAR.

If the DRX is configured, the MAC entity of the UE performs thefollowings in every subframe (or slot, symbol, or time unit set by RRC).

-   -   When DRX Command MAC CE or Long DRX Command MAC CE is received,

stop onDurationTimer and drx-Inactivity Timer.

-   -   When the drx-Inactivity Timer expires or the DRX Command MAC CE        is received,        -   if the short DRX cycle is configured, (re)start the            drxShortCycleTimer, use the short DRX cycle, and use a band            indicated by the drx_BandIndex_shortDRX-Cycle.        -   if the short DRX cycle is not configured, use the long DRX            cycle, and use a band indicated by the            drx_BandIndex_longDRX-Cycle.    -   When the drxShortCycleTimer expires, use the long DRX cycle, and        use a band indicated by the drx_BandIndex_longDRX-Cycle.    -   When the drxShortCycleTimer has not expired and when the Long        DRX Command MAC CE is received,

stop the drxShortCycleTimer, use the long DRX cycle, and use a bandindicated by the drx_BandIndex_longDRX-Cycle.

-   -   When the UE is using the short DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe        number]modulo(shortDRX-Cycle)=(drxStartOffset)modulo(shortDRX-Cycle).    -   When the UE is using the long DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe number]modulo(longDRX-Cycle)=drxStartOffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot,symbol, or time unit set by RRC) in which the PDCCH is present in ActiveTime. If the PDCCH indicates DL transmission in this subframe, or if aDL assignment is set in this subframe, the UE starts the HARQ RTT timerfor the corresponding HARQ process and stops the drx-RetransmissionTimerfor the same HARQ process.

If the PDCCH indicates UL transmission in this subframe, or if an ULgrant is set in this subframe, the UE starts the UL HARQ RTT timer forthe HARQ process of the subframe including the last retransmission ofcorresponding PUSCH transmission. Also, the UE stops theDRX_ULRetransmissionTimer for the same HARQ process.

If the PDCCH indicates a new transmission, the UE (re)starts thedrx-InactivityTimer.

Embodiment 4-6

The embodiment 4-6 shows an operation procedure that supports case C6730 in FIG. 67 .

A MAC entity may be configured to have a DRX function for controllingthe PDCCH monitoring of the UE by the RRC. If the DRX is configured whenthe UE is in the RRC_CONNECTED state, the MAC entity may discontinuouslymonitor the PDCCH according to the described DRX operation. When usingthe DRX operation, the MAC entity should monitor the PDCCH by using aspecific band at a specific time according to the specific requirements.At least one of the following parameters is configured for the DRXoperation: drx_BandIndex, onDurationTimer, drx-InactivityTimer,drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle,drxStartOffset, drxShortCycleTimer, shortDRX-Cycle.

The drx_BandIndex related to the band may be included in the DRXconfiguration or may be defined with an index of the band configured asa default band or a primary band in the band configuration included inthe RRC Connection(re-)Configuration procedure without being included inthe DRX configuration.

For example, it may be indicated as drx_BandIndex=defaultBandIndex, ordrx_BandIndex=primaryBandIndex.

If the DRX cycle is configured, the MAC entity of the UE operates inactive time in case of the follows:

-   -   when at least one of onDurationTimer, drx-InactivityTimer,        drx-RetransmissionTimer, drx-ULRetransmissionTimer, and        mac-ContentionResolutionTimer is running,    -   when scheduling request (SR) is sent to PUCCH and pending,    -   when a UL grant for unsent HARQ retransmission can occur, and    -   when a control signal is generated for the first transmission on        the PDCCH after receiving the RAR.

If the DRX is configured, the MAC entity of the UE performs thefollowings in every subframe (or slot, symbol, or time unit set by RRC).

-   -   When DRX Command MAC CE or Long DRX Command MAC CE is received,

stop onDurationTimer and drx-Inactivity Timer.

-   -   When the current Active Band is not equal to a band indicated by        the drx_BandIndex;        -   if the drx-Inactivity Timer expires,            -   use a band indicated by the drx_BandIndex, and            -   (re)start the drx-InactivityTimer.    -   When the current Active Band is equal to a band indicated by the        drx_BandIndex;        -   if the drx-Inactivity Timer expires or if the DRX Command            MAC CE is received,            -   if the short DRX cycle is configured, (re)start the                drxShortCycleTimer and use the short DRX cycle.            -   if the short DRX cycle is not configured, use the long                DRX cycle.        -   if the drxShortCycleTimer expires, use the long DRX cycle.        -   if the drxShortCycleTimer has not expired, and if the Long            DRX Command MAC CE is received,

stop the drxShortCycleTimer and use the long DRX cycle.

-   -   When the UE is using the short DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe        number]modulo(shortDRX-Cycle)=(drxStartOffset)modulo(shortDRX-Cycle).    -   When the UE is using the long DRX cycle and satisfies the        following equation according to current SFN and subframe values,        start the onDurationTimer.        [(SFN*10)+subframe number]modulo(longDRX-Cycle)=drxStartOffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot,symbol, or time unit set by RRC) in which the PDCCH is present in ActiveTime. If the PDCCH indicates DL transmission in this subframe, or if aDL assignment is set in this subframe, the UE starts the HARQ RTT timerfor the corresponding HARQ process and stops the drx-RetransmissionTimerfor the same HARQ process.

If the PDCCH indicates UL transmission in this subframe, or if an ULgrant is set in this subframe, the UE starts the UL HARQ RTT timer forthe HARQ process of the subframe including the last retransmission ofcorresponding PUSCH transmission. Also, the UE stops theDRX_ULRetransmissionTimer for the same HARQ process.

If the PDCCH indicates a new transmission, the UE (re)starts thedrx-InactivityTimer.

In the inter-band timer-based switching operation of the disclosure, theband to which the UE moves due to the timer expiration may be determinedaccording to one of the following methods.

1) In case of switching from band 1 to band 2, return to band 1 due tothe timer expiration.

2) Set a band for switching per timer

3) Return to the previous band due to the timer expiration

4) Return to a band of given priority due to the timer expiration

The inter-band timer-based switching operation of the disclosure is asfollows.

FIG. 68 is a diagram illustrating a timer-based band switching operationaccording to an embodiment of the disclosure n.

Referring to FIG. 68 , when a given condition or a condition configuredby the base station is satisfied, the terminal triggers a timer for oneband at operation S6810. Some of operation characteristics of the timer,for example, a timer increase/decrease time, a timer increase/decreasevalue, and a timer expiration value may be given in advance orconfigured by the base station.

Depending on whether the condition is satisfied, the terminal may startthe timer or increase or decrease a timer value. When the current valueof the timer reaches the timer expiration value, the terminal switchesfrom a current band (the first band) to another band (the second band)at operation S6820. Also, the terminal stops the timer operation for thefirst band.

The second band to which the terminal will switch may be given inadvance or configured by the base station.

FIG. 69 is a diagram illustrating another timer-based band switchingoperation according to an embodiment of the disclosure.

Referring to FIG. 69 , when the terminal receives a schedulingindication for the first band from the base station at operation S6910,the terminal triggers a timer for the first band at operation S6920.According to a predetermined rule, the timer increases or decreases by acertain amount in time.

Then, at operation S6930, the terminal determines whether the timerexpires. If the scheduling indication for the first band is receivedagain even though the timer does not expire, the terminal restarts thetimer for the first band.

When the timer value reaches a given timer expiration value, theterminal switches from the first band to the second band at operationS6940. Also, the terminal stops the timer operation for the first band.

FIG. 70 is a diagram illustrating still another timer-based bandswitching operation according to an embodiment of the disclosure.

Referring to FIG. 70 , when an indication of switching from thecurrently operating band to the first band is received from the basestation at operation S7010, the terminal triggers a timer for the firstband at operation S7020. According to a predetermined rule, the timerincreases or decreases by a certain amount in time.

Then, at operation S7030, the terminal determines whether the timerexpires. If the scheduling indication for the first band is receivedagain even though the timer does not expire, the terminal restarts thetimer for the first band.

When the timer value reaches a given timer expiration value, theterminal switches from the first band to the second band at operationS7040. Also, the terminal stops the timer operation for the first band.

FIG. 71 is a diagram illustrating yet another timer-based band switchingoperation according to an embodiment of the disclosure.

Referring to FIG. 71 , when an indication of switching to the first bandis received from the base station at operation S7110, the terminaltriggers a timer for the first band at operation S7120.

If the terminal that operates in the first band does not receive ascheduling indication for the first band at a given time at operationS7130, the terminal proceeds with the timer for the first band atoperation S7140 so that the timer value is increased or decreased by agiven amount according to a predetermined rule.

If the scheduling indication for the first band is received even thoughthe timer for the first band does not expire, the terminal restarts thetimer for the first band. When the timer value reaches a given timerexpiration value at operation S7150, the terminal switches from thefirst band to the second band at operation S7160. Also, the terminalstops the timer operation for the first band.

FIG. 72 is a diagram illustrating a configuration of a terminalaccording to an embodiment of the disclosure.

Referring to FIG. 72 , the terminal may include a transceiver 7210 fortransmitting/receiving a signal to/from any other device, and acontroller 7220 for controlling all operations of the terminal. In thedisclosure, the controller 7220 may be defined as a circuit, anapplication specific integrated circuit, or at least one processor.

The controller 7220 may perform the above-described operations accordingto various embodiments of the disclosure, including a BW controller7221, a DRX controller 7222, and a system time controller 7223. Forexample, the controller 7220 may control a signal flow betweenrespective blocks to perform operations according to the first to fourthembodiments described above. However, the controller 7220 and thetransceiver 7110 are not necessarily implemented as separateapparatuses, and may be implemented as a single unit in the form of asingle chip.

FIG. 73 is a diagram illustrating a configuration of a base stationaccording to an embodiment of the disclosure.

Referring to FIG. 73 , the base station may include a transceiver 7310,a controller 7320, and a memory 7330 (i.e., a storage device). In thedisclosure, the controller may be defined as a circuit, an applicationspecific integrated circuit, or at least one processor.

The transceiver 7310 may transmit and receive signals. The controller7320 may control the overall operation of the base station according tothe first to fourth embodiments of the disclosure. For example, thecontroller 7320 may control a signal flow between respective blocks toperform operations according to the first to fourth embodimentsdescribed above.

It is to be noted that structures, procedures, operations, functions,and the like described above and illustrated in the drawings are notintended to limit the scope of the disclosure. That is, it should not beconstrued that all of the described or illustrated elements areessential for the implementation of the disclosure.

The above-described operations of the base station and the terminal canbe realized by providing a memory device storing program codes to anarbitrary component equipped in the base station or the terminal. Thatis, the controller of the base station or terminal may execute theabove-described operations by reading and executing the program codesstored in the memory device by a processor or a central processing unit(CPU).

Various components, modules, etc. of the entity, base station, orterminal described herein may be implemented in a hardware circuit,e.g., a complementary metal oxide semiconductor (CMOS) based logiccircuit, a firmware, a software, or a combination thereof. In oneexample, various electrical structures and methods may be implementedusing electrical circuits such as transistors, logic gates, and customsemiconductors.

Meanwhile, in the drawings illustrating the method of the disclosure,the order of description does not necessarily correspond to the order ofexecution, and the relationship of order may be changed or executed inparallel.

In addition, the drawings illustrating the method of the disclosure mayomit some of elements and include only some of elements within the scopeof the disclosure.

Further, the above-discussed embodiments of the disclosure may becombined and executed or only some components thereof may be combinedand executed within the scope of the disclosure.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a terminal in a wirelesscommunication system, the method comprising the following ordered steps:transmitting, to a base station, a capability message includinginformation associated with a switching delay time; receiving, from thebase station, a radio resource control (RRC) message includinginformation on a first band; receiving, from the base station, downlinkcontrol information (DCI) associated with band switching; andperforming, based on the DCI, the band switching to a second band withina duration determined based on the information associated with theswitching delay time.
 2. The method of claim 1, further comprising:starting a timer associated with the second band for falling back fromthe second band to the first band; and performing band switching to thefirst band in response to the timer expiring, wherein the RRC messageincludes a duration of the timer.
 3. The method of claim 1, furthercomprising: after performing the band switching to the second band,receiving, from the base station, data on the second band.
 4. The methodof claim 2, further comprising: restarting the timer in case that secondDCI is received before the timer expires, wherein the DCI is first DCI.5. A method performed by a base station in a wireless communicationsystem, the method comprising the following ordered steps: receiving,from a terminal, a capability message including information associatedwith a switching delay time; transmitting, to the terminal, a radioresource control (RRC) message including information on a first band;transmitting, to the terminal, downlink control information (DCI)associated with band switching; and transmitting, to the terminal, dataon a second band based on the DCI, wherein the band switching to thesecond band is performed based on the DCI within a duration, and whereinthe duration is determined based on the information associated with theswitching delay time.
 6. The method of claim 5, wherein a timerassociated with the second band is started for the terminal to fall backfrom the second band to the first band, and wherein data is transmittedon the first band based on the timer expiring.
 7. The method of claim 6,wherein the RRC message includes a duration of the timer.
 8. The methodof claim 6, wherein the timer is restarted in case that second DCI istransmitted before the timer expires, and wherein the DCI is first DCI.9. A terminal in a wireless communication system, the terminalcomprising: a transceiver; and a controller coupled with the transceiverand configured to perform the following ordered steps to: transmit, to abase station, a capability message including information associated witha switching delay time, receive, from the base station, a radio resourcecontrol (RRC) message including information on a first band, receive,from the base station, downlink control information (DCI) associatedwith band switching, and perform, based on the DCI, the band switchingto a second band within a duration determined based on the informationassociated with the switching delay time.
 10. The terminal of claim 9,wherein the controller is further configured to: start a timerassociated with the second band for falling back from the second band tothe first band, and perform band switching to the first band in responseto the timer expiring, and wherein the RRC message includes a durationof the timer.
 11. The terminal of claim 9, wherein the controller isfurther configured to receive, from the base station, data on the secondband after performing the band switching to the second band.
 12. Theterminal of claim 10, wherein the controller is further configured torestart the timer in case that second DCI is received before the timerexpires, and wherein the DCI is first DCI.
 13. A base station in awireless communication system, the base station comprising: atransceiver; and a controller coupled with the transceiver andconfigured to perform the following ordered steps to: receive, from aterminal, a capability message including information associated with aswitching delay time, transmit, to the terminal, a radio resourcecontrol (RRC) message including information on a first band, transmit,to the terminal, downlink control information (DCI) associated with bandswitching, and transmit, to the terminal, data on a second band based onthe DCI, wherein the band switching to the second band is performedbased on the DCI within a duration, and wherein the duration isdetermined based on the information associated with the switching delaytime.
 14. The base station of claim 13, wherein a timer associated withthe second band is started for the terminal to fall back from the secondband to the first band, and wherein data is transmitted on the firstband based on the timer expiring.
 15. The base station of claim 14,wherein the RRC message includes a duration of the timer.
 16. The basestation of claim 14, wherein the timer is restarted in case that secondDCI is transmitted before the timer expires, and wherein the DCI isfirst DCI.